User Guide - static.huaweicloud.com · HUAWEI TECHNOLOGIES CO., LTD. ... l Expand the capacity of an EVS disk. l Create an EVS disk backup. ... lists the EVS monitoring metrics.

Elastic Volume Service

User Guide

Issue 06

Date 2017-04-22

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2017. All rights reserved.No part of this document may be reproduced or transmitted in any form or by any means without prior writtenconsent of Huawei Technologies Co., Ltd. Trademarks and Permissions

and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.All other trademarks and trade names mentioned in this document are the property of their respectiveholders. NoticeThe purchased products, services and features are stipulated by the contract made between Huawei and thecustomer. All or part of the products, services and features described in this document may not be within thepurchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information,and recommendations in this document are provided "AS IS" without warranties, guarantees orrepresentations of any kind, either express or implied.

The information in this document is subject to change without notice. Every effort has been made in thepreparation of this document to ensure accuracy of the contents, but all statements, information, andrecommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd.Address: Huawei Industrial Base

Bantian, LonggangShenzhen 518129People's Republic of China

Website: http://www.huawei.com

Email: [email protected]

Issue 06 (2017-04-22) Huawei Proprietary and ConfidentialCopyright © Huawei Technologies Co., Ltd.

i

http://www.huawei.com

mailto:[email protected]

Contents

1 Overview......................................................................................................................................... 11.1 Description......................................................................................................................................................................21.2 EVS Disk Device Types................................................................................................................................................. 21.3 Shared EVS Disks.......................................................................................................................................................... 21.4 EVS Disk Functions....................................................................................................................................................... 31.5 EVS Disk Types..............................................................................................................................................................31.6 EVS Charging Standards................................................................................................................................................ 41.7 Relationships with Other Services..................................................................................................................................4

2 Getting Started............................................................................................................................... 62.1 Operation Procedure....................................................................................................................................................... 72.2 Purchasing an EVS Disk.................................................................................................................................................72.3 Initializing an EVS Disk (Windows)............................................................................................................................ 122.4 Initializing an EVS Disk (Linux)..................................................................................................................................17

3 Operation Guide..........................................................................................................................223.1 Managing EVS Disks................................................................................................................................................... 233.2 Expanding Capacity of an EVS Disk (Windows).........................................................................................................243.3 Expanding Capacity of an EVS Disk (Linux).............................................................................................................. 313.4 Backing Up EVS Disks................................................................................................................................................ 38

4 FAQs...............................................................................................................................................404.1 What Is Elastic Volume Service?..................................................................................................................................414.2 What Are the Types of EVS Disks?............................................................................................................................. 414.3 What Are EVS Disk Specifications?............................................................................................................................ 414.4 How Is the EVS Disk Performance?............................................................................................................................ 414.5 How Many EVS Disks Can Be Attached to a Server?................................................................................................. 424.6 Can I Attach an EVS Disk to Multiple Servers?.......................................................................................................... 424.7 How Can I Attach an EVS Disk to a Server?............................................................................................................... 424.8 Can EVS Disk Capacity Be Changed?......................................................................................................................... 424.9 Is Disk Capacity Expansion Supported?...................................................................................................................... 424.10 How Can I Expand EVS Disk Capacity?................................................................................................................... 424.11 How Many EVS Disks Can I Purchase?.....................................................................................................................434.12 Will Data in the EVS Disk Be Lost When the EVS Disk Is Detached?.....................................................................434.13 How Many Status Types Does an EVS Disk Have? What Does Each Status Type Mean?....................................... 43

Elastic Volume ServiceUser Guide Contents


ii

4.14 What Should I Do If an Error Occurs on My EVS Disk?.......................................................................................... 454.15 What Are the ECS Types Supported by EVS Disks for Which Device Type Is SCSI?............................................. 464.16 What Is a Shared EVS Disk?......................................................................................................................................47

A Change History........................................................................................................................... 51

Elastic Volume ServiceUser Guide Contents


iii

1 Overview

1.1 Description

1.2 EVS Disk Device Types

1.3 Shared EVS Disks

1.4 EVS Disk Functions

1.5 EVS Disk Types

1.6 EVS Charging Standards

1.7 Relationships with Other Services

Elastic Volume ServiceUser Guide 1 Overview


1

1.1 DescriptionElastic Volume Service (EVS) disks are scalable virtual block storage devices designedbased on the distributed architecture. You can create EVS disks online and attach them toservers. A server can be an Elastic Cloud Server (ECS) or a Bare Metal Server (BMS). Themethod for using EVS disks is the same as that for using hard disks on physical servers.Compared with traditional hard disks, EVS disks have higher data reliability and I/Othroughput capabilities. They are also easier to use. EVS disks apply to file systems,databases, and system software and applications that require block storage devices.

EVS disks are also called disks.

1.2 EVS Disk Device TypesEVS disks have two device types, and they are Virtual Block Device (VBD) and SmallComputer System Interface (SCSI).

l VBD: When you create EVS disks on the management console, Device Type of the EVSdisk is VBD by default. These EVS disks support only basic SCSI read and writecommands.

l SCSI: You can also create EVS disks for which Device Type is SCSI on the managementconsole. These EVS disks support transparent SCSI command transmission, allowing theserver OS to directly access underlying storage media. EVS disks for which Device Typeis SCSI support both basic and advanced SCSI commands.

NOTE

l For details about the supported ECS types, OSs, and ECS software requirements, see WhatAre the ECS Types Supported by EVS Disks For Which Device Type Is SCSI?.

l Only EVS disks for which Device Type is SCSI can be attached to BMSs. For details, see theBare Metal Server User Guide.

1.3 Shared EVS DisksYou can create both shared EVS disks and non-shared EVS disks on the management console.

l A non-shared EVS disk can be attached to only a server.

l A shared EVS disk can be attached to multiple servers. Currently, only data disks can beused as shared EVS disks, whereas system disks cannot be used as shared EVS disks.

The shared EVS disk constraints and restrictions are as follows:

– Only data disks can be used as shared EVS disks, whereas system disks cannot beused as shared EVS disks.

– Shared EVS disk backups cannot be used to create new EVS disks.

You can create shared EVS disks for which Device Type is set to either VBD or SCSI.

l Shared EVS disks for which Device Type is VBD: The device type of the created sharddisks is VBD by default.

l Shared EVS disks for which Device Type is SCSI: These EVS disks support SCSIreservations.



2

http://www.hwclouds.com/product/evs.html

If shared EVS disks for which Device Type is SCSI are attached to an ECS, SCSIreservations take effect only when such disks are used together with the anti-affinitypolicy of an ECS group.

NOTICETo improve data security, you are advised to use SCSI reservations together with theanti-affinity policy of an ECS group. Shared EVS disks for which Device Type is SCSIcan be attached to ECSs in the same ECS group. Do not attach such EVS disks to ECSsnot belonging to any ECS group. Otherwise, SCSI reservations may not work properly,which may put data at risk.

NOTE

l The anti-affinity policy of an ECS group allows you to create ECSs on different hosts, therebyimproving service reliability. This function does not apply to existing ECSs. You cannot addexisting ECSs to an ECS group.

For details about ECS groups, see section (Optional) Creating an ECS Group in the ElasticCloud Server User Guide.

l The SCSI reservation mechanism uses a SCSI Reservation command to perform SCSIreservation operations. If an ECS sends such a command to an EVS disk, the disk displayed aslocked to other ECSs, preventing the data damage that may be caused by simultaneous readand write operations to the disk from multiple ECSs.

l Relationship between ECS groups and SCSI reservations: SCSI reservation on a single EVSdisk cannot differentiate multiple ECSs on the same physical host. In this case, SCSIreservations are supported only when ECSs belong to different physical hosts. Servers belongto the same physical host but not the same anti-affinity ECS group also do not support SCSIreservation. In this case, you are advised to use SCSI reservation command together with theanti-affinity policy of an ECS group.

1.4 EVS Disk FunctionsEVS provides hard disk resources for servers. With EVS, you can:

l Purchase an EVS disk.l Attach an EVS disk to a server.l Expand the capacity of an EVS disk.l Create an EVS disk backup.l Detach an EVS disk.l Delete an EVS disk.l Query an EVS disk.

1.5 EVS Disk TypesThree types of EVS disks are provided: ultra-high I/O, high I/O, and common I/O.

EVS disks with different I/O capacities provide different features at different prices. ChooseEVS disks based on your requirements.l EVS disks with ultra-high I/O



3



EVS disks that use solid state disk (SSD). These EVS disks provide ultra-high I/O andlow latency. They support NoSQL, RDS, and data warehouse applications.

l EVS disks with high I/OEVS disks that use serial attached SCSI (SAS). These EVS disks provide high I/O andlow latency. They support RDS, NoSQL, data warehouse, and file system applications.

l EVS with common I/OEVS disks that use Serial Advanced Technology Attachment (SATA). These EVS disksprovide reliable block storage and can run key applications.

1.6 EVS Charging StandardsEVS disk charging standards are made based on factors, such as capacity, type, and useduration. You can pay for EVS disks in Metered or Yearly/Monthly mode. For details, seeTable 1-1.

Table 1-1 EVS charging standards

Charging Item

ProductType

Description

StepSpecifications

Unit ByHour

ByMonth

ByYear

EVS Common I/O

Linearcharging

1 GB Yuan perGB

0.000667

0.32 3.2

EVS HighI/O

Linearcharging

1 GB Yuan perGB

0.002229

1.07 10.7

EVS Ultra-high I/O

Linearcharging

1 GB Yuan perGB

0.005208

2.5 25

1.7 Relationships with Other Servicesl ECS: EVS disks can be attached to ECSs and can be used as scalable block storage

devices.l BMS: EVS disks for which Device Type is SCSI can be attached to BMSs and used as

scalable block storage devices.l Volume Backup Service (VBS): The VBS service can back up EVS disk data to ensure

the reliability and security of the server data.l Cloud Eye (CES): After enabling the EVS service, you can use the CES service to view

the status of monitored service objects without installing additional plug-ins. Table 1-2lists the EVS monitoring metrics.



4

http://www.hwclouds.com/product/rds.html

http://www.hwclouds.com/en-us/product/rds.html

http://www.hwclouds.com/product/vbs.html

Table 1-2 EVS monitoring metrics

Metric Definition Monitored Object

Formula

Disk ReadRate

This metric is used to show thenumber of bytes read from themonitored object per second(bytes/second).

EVS disks Total number of bytesread from an EVS diskattached to the server/Monitoring period

Disk WriteRate

This metric is used to show thenumber of bytes written to themonitored object per second(bytes/second).

EVS disks Total number of byteswritten to an EVS diskattached to the server/Monitoring period

Disk ReadRequests

This metric is used to show thenumber of read requests sent tothe monitored object persecond (requests/second).

EVS disks Total number ofrequests for readingdata from an EVS diskattached to the server/Monitoring period

Disk WriteRequests

This metric is used to show thenumber of write requests sentto the monitored object persecond (requests/second).

EVS disks Total number ofrequests for writingdata to an EVS diskattached to the server/Monitoring period



5

2 Getting Started

2.1 Operation Procedure

2.2 Purchasing an EVS Disk

2.3 Initializing an EVS Disk (Windows)

2.4 Initializing an EVS Disk (Linux)

Elastic Volume ServiceUser Guide 2 Getting Started


6

2.1 Operation ProcedureFigure 2-1 shows the process of EVS disk-related operations.

Figure 2-1 Operation procedure flow chart

2.2 Purchasing an EVS Disk

PrecautionsWhen the server is created, the system disk is automatically added. You do not need toindependently purchase the system disk.

You can purchase data disks during or after the server creation. If you create data disks duringthe server creation, the system automatically attaches the data disks to the server. If youpurchase data disks after the server creation, you must manually attach the purchased datadisks to the server.

Purchasing an EVS Disk

Step 1 Log in to official website of Huawei Enterprise Cloud.



7

http://www.hwclouds.com/en-us/

Step 2 Click Register in the upper right corner of the page.

On the displayed Register page, register an account as prompted. For details, see Register onHuawei Enterprise Cloud Management Console.

After you have successfully registered, the system automatically redirects you to yourpersonal information page.

Step 3 Return to the homepage of Huawei Enterprise Cloud and click Elastic Volume Service(EVS) in the Various Products area.

The page for you to purchase EVS disks is displayed.

Step 4 Click Buy Now.

Step 5 Configure the basic information about the EVS disk, as shown in Table 2-1.

NOTE

You can also click Create from backup to create new EVS disks using backup data. For details, seeCreate an EVS Disk Using a VBS Backup in section Data Restoration Using a VBS Backupprovided in the Volume Backup Service User Guide.

Table 2-1 Parameter description

Parameter Description Remarks

AZ MandatorySpecifies the availability zone (AZ)within which the EVS disk is to becreated.

The AZ of the EVS diskmust be the same as that ofthe server to be attached to.

Capacity MandatorySpecifies the disk size (GB).The parameter value is as follows:l System disk: 40 GB to 32768 GBl Data disk: 100 GB to 32768 GB

If you use a backup tocreate an EVS disk, the diskcapacity must be greaterthan or equal to the backupsize. When the disk capacityis not specified, the size ofthe disk is the same as thesize of the backup.The maximum number ofEVS disks as well as themaximum disk capacityallowed to purchase aredisplayed. To ensureeffective resource usage, anupper limit is set on thecapacity of EVS disks to bepurchased. If the capacity ofthe EVS disks you needexceeds the upper limit,click Apply for HigherQuota to obtain higherquota. You can purchase theEVS disks you need afterthe request is approved.



8

http://support.hwclouds.com/en-us/qs-consolehome/en-us_topic_0016739341.html

http://support.hwclouds.com/en-us/qs-consolehome/en-us_topic_0016739341.html

http://www.hwclouds.com/en-us/


Disk Name OptionalThe disk name can contain letters,digits, hyphens (-), and underscores(_), and cannot exceed 64 characters.l If you create disks one by one, this

parameter value is used as theactual disk name.

l If you create disks in batches, thisparameter value is used as theprefix of disk names, and the diskname is in the Disk name-4 digitformat.

For example, if you createtwo disks and use volumeas the disk name, the EVSdisk names will bevolume-0001 andvolume-0002.

Disk Type Mandatoryl Common I/O: EVS disks that use

Serial Advanced TechnologyAttachment (SATA). These EVSdisks provide reliable blockstorage services and can run keyapplications.

l High I/O: EVS disks that use serialattached SCSI (SAS). These EVSdisks have high I/O, low latencyand support RDS, NoSQL, datawarehouse, and file systemapplications.

l Ultra-high I/O: EVS disks that usesolid state disk (SSD). These EVSdisks have ultra-high I/O, lowlatency and support RDS, NoSQL,and data warehouse applications.



9


Device Type Optionall If SCSI is not selected, the EVS

disk device type is VBD bydefault.

l If SCSI is selected, Device Typeof the created EVS disk is SCSI.This type of EVS disks allowsECS OS to directly accessunderlying storage media andsupport advanced SCSI commandscompared with EVS disks forwhich Device Type is VBD.

NOTE

l For details about the EVS disk devicetypes, see EVS Disk Device Types.

l For details about the supported ECStypes, OSs, and ECS softwarerequirements, see What Are the ECSTypes Supported by EVS Disks ForWhich Device Type Is SCSI?.

SCSI

Disk Sharing OptionalIf Share is selected, a shared EVSdisk is created, and the shared diskcan be simultaneously attached tomultiple ECSs.If SCSI and share are both selected, ashared EVS disk for which DeviceType is SCSI is created.NOTE

For details about shared EVS disks andshared EVS disks for which Device Typeis SCSI, see Shared EVS Disks.

Shared disk

Charging Mode MandatoryYou can pay for EVS disks in twoways:l Yearly/Monthlyl Metered

None



10


Quantity MandatorySpecifies the number of disks to becreated in batches. The default valueis set to 1, which means only one diskis created. Currently, you can createup to 100 disks at a time.NOTE

If EVS disks are created using backups,batch creation is not supported, and thisparameter must be set to 1.

The maximum number ofEVS disks you are allowedto purchase is displayed. Toensure effective resourceusage, an upper limit is seton the number of EVS disksto be purchased. If thenumber of the EVS disksyou need exceeds the upperlimit, click Apply forHigher Quota to obtainhigher quota. You canpurchase the EVS disks youneed after the request isapproved.

Valid Period MandatoryMandatory if you select Yearly/Monthly to pay for the EVS disksThe valid period ranges from 1 monthto 3 years.

None

Step 6 Click Buy Now.

Step 7 Confirm EVS disk information, and read and agree to the service agreement.

Step 8 Click Submit Order.

Step 9 Pay for EVS disks as prompted and click OK.

The homepage of Elastic Volume Service is displayed.

Step 10 After the EVS disk is created and its status changes to Available, locate the row that containsthe EVS disk and click Attach in the Operation column.

Step 11 In the displayed dialog box, select the server to which the disk is to be attached. Select themount point from the drop-down list and click Attach.

The mount point is the drive letter of the EVS disk to be attached to the server. The mountpoint for each EVS disk must be unique on a server.

Return to the disk list page. If the disk status changes to In-use, the EVS disk is successfullyattached to the server.

Step 12 Initialize the data disk.

For details, see 2.3 Initializing an EVS Disk (Windows) or 2.4 Initializing an EVS Disk(Linux).

----End



11

2.3 Initializing an EVS Disk (Windows)

ScenariosThe method for initializing EVS disks varies depending on the operating system (OS) runningon a server. This section uses the Windows Server 2008 R2 Enterprise OS to describe how toinitialize an EVS disk of the server running Windows. For details about initializing the EVSdisks of servers running other Windows OSs, see the OS product documentation.

EVS disks can be used only after being initialized in either of the following scenarios:

l EVS disks are added to servers during server creation.l New EVS disks are attached to servers for capacity expansion.

Prerequisitesl You have logged in to the server.

– For details about how to log in to an ECS, see section Logging In to an ECS in theElastic Cloud Server User Guide.

– For details about how to log in to a BMS, see section Logging In to a BMS in theBare Metal Server User Guide.

l EVS disks have been attached to the server and have not been initialized.

Procedure

Step 1 In the server desktop, right-click Computer and choose Manage from the shortcut menu.

The Server Manager page is displayed.

Step 2 In the navigation tree, choose Storage > Disk Management.

Step 3 In the right pane, a disk list is displayed, and the Initialize Disk dialog box is displayedlisting the disks need to be initialized. Select MBR (Master Boot Record) and click OK, asshown in Figure 2-2.



12

http://support.hwclouds.com/usermanual-ecs/en-us_topic_0013771089.html

Figure 2-2 Unallocated disks

Step 4 Right-click the unallocated area on the disk and choose New Simple Volume from theshortcut menu, as shown in Figure 2-3.

Figure 2-3 Creating a simple disk

Step 5 On the displayed New Simple Volume Wizard page, click Next.



13

Figure 2-4 New simple volume wizard

Step 6 Specify the simple volume size as required (the default value is the maximum) and clickNext.

Figure 2-5 Specifying the volume size

Step 7 Assign the driver letter and click Next.



14

Figure 2-6 Assigning the driver letter or path

Step 8 Format the new partition by the configuration parameters and click Next.

Figure 2-7 Formatting the partition



15

Figure 2-8 Completing the partition creation

Step 9 Click Finish to complete the wizard. Wait for the initialization to complete. When the volumestatus changes to Healthy, the initialization is successful, as shown in Figure 2-9.

Figure 2-9 Successful disk initialization

----End



16

2.4 Initializing an EVS Disk (Linux)

Scenarios

The method for initializing EVS disks varies depending on the operating system (OS) runningon a server. This section uses the CentOS 7.0 64-bit OS to describe how to initialize an EVSdisk of the server running Windows. For details about initializing the EVS disks of serversrunning other Windows OSs, see the OS product documentation.

An EVS disk can be used only after being initialized in either of the following scenarios:

l An EVS disk is attached to a server and used as the data disk after the server creation.l A new EVS disk is attached to a server for capacity expansion.

Prerequisitesl Log in to the server as user root.

– For details about how to log in to an ECS, see section Logging In to an ECS in theElastic Cloud Server User Guide.

– For details about how to log in to a BMS, see section Logging In to a BMS in theBare Metal Server User Guide.

l An EVS disk has been attached to a server and has not been initialized.

Creating Partitions and Attaching a Disk

The following operations are used as an example. When a new data disk is attached to aserver, the disk must be set as the primary partition in ext4 format and be automaticallyattached to the /mnt/sdc directory upon start.

Step 1 Run the following command to query information about the newly added EVS disk:

fdisk -l

If information similar to the following is displayed, the server contains two disks. /dev/xvdais used as the system disk, and /dev/xvdb is the newly added data disk.

[root@ecs-b656 test]# fdisk -l

Disk /dev/xvda: 42.9 GB, 42949672960 bytes, 83886080 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk label type: dosDisk identifier: 0x000cc4ad

Device Boot Start End Blocks Id System/dev/xvda1 * 2048 2050047 1024000 83 Linux/dev/xvda2 2050048 22530047 10240000 83 Linux/dev/xvda3 22530048 24578047 1024000 83 Linux/dev/xvda4 24578048 83886079 29654016 5 Extended/dev/xvda5 24580096 26628095 1024000 82 Linux swap / Solaris

Disk /dev/xvdb: 10.7 GB, 10737418240 bytes, 20971520 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytes



17

http://support.hwclouds.com/usermanual-ecs/en-us_topic_0013771089.html

Step 2 Run the following command to switch to the fdisk mode:

fdisk Newly added data disk

/dev/xvdb is used as an example.

fdisk /dev/xvdb

Information similar to the following is displayed:

[root@ecs-b656 test]# fdisk /dev/xvdbWelcome to fdisk (util-linux 2.23.2).Changes will remain in memory only, until you decide to write them.Be careful before using the write command.Device does not contain a recognized partition tableBuilding a new DOS disklabel with disk identifier 0xb00005bd.Command (m for help):

Step 3 Enter n and press Enter to create partitions.

Enter n to add a partition.


l p indicates the primary partition.l e indicates the extended partition.Command (m for help): nPartition type: p primary (0 primary, 0 extended, 4 free) e extended

Step 4 Enter p and press Enter to create a primary partition as an example.

Information similar to the following is displayed: (Partition number indicates the serialnumber of the primary partition. The value can be 1 to 4.)

Select (default p): pPartition number (1-4, default 1):

Step 5 Enter the number of the primary partition and press Enter. Primary partition number 1 is usedas an example.

Information similar to the following is displayed: (First sector indicates the start cylindernumber. The value can be 2048 to 20971519, and the default value is 2048.)

Partition number (1-4, default 1): 1First sector (2048-20971519, default 2048):

Step 6 Select the default start cylinder number 2048 and press Enter.

Information similar to the following is displayed: (Last sector indicates the end cylindernumber. The value can be 2048 to 20971519, and the default value is 20971519.)

First sector (2048-20971519, default 2048):Using default value 2048Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519):

Step 7 Select the default end cylinder number 20971519 and press Enter.

Information similar to the following is displayed: (A primary partition is created for a 10-GBdata disk.)

Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519):Using default value 20971519Partition 1 of type Linux and of size 10 GiB is setCommand (m for help):



18

Step 8 Enter p and press Enter to view the created partition.

Information similar to the following is displayed: (Details about the /dev/xvdb1 partition aredisplayed.)

Command (m for help): p

Disk /dev/xvdb: 10.7 GB, 10737418240 bytes, 20971520 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk label type: dosDisk identifier: 0xb00005bd

Device Boot Start End Blocks Id System/dev/xvdb1 2048 20971519 10484736 83 Linux

Command (m for help):

Step 9 Enter w and press Enter to write the partition result to the partition table.

Information similar to the following is displayed: (The partition is successfully created.)

Command (m for help): wThe partition table has been altered!

Calling ioctl() to re-read partition table.Syncing disks.

Step 10 Run the following command to synchronize the new partition table to the data disk:

partprobe

Step 11 Run the following command to set the format for the file system of the newly createdpartition:

mkfs -t File system format /dev/xvdb1

The ext4 file format is used as an example.

mkfs -t ext4 /dev/xvdb1


[root@ecs-b656 test]# mkfs -t ext4 /dev/xvdb1mke2fs 1.42.9 (28-Dec-2013)Filesystem label=OS type: LinuxBlock size=4096 (log=2)Fragment size=4096 (log=2)Stride=0 blocks, Stripe width=0 blocks655360 inodes, 2621184 blocks131059 blocks (5.00%) reserved for the super userFirst data block=0Maximum filesystem blocks=215167795280 block groups32768 blocks per group, 32768 fragments per group8192 inodes per groupSuperblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632

Allocating group tables: doneWriting inode tables: doneCreating journal (32768 blocks): doneWriting superblocks and filesystem accounting information: done

The initialization takes a period of time. Observe the system running status, and do not exit.



19

Step 12 Run the following command to create a mounting directory:

mkdir Mounting directory

/mnt/sdc is used as an example.

mkdir /mnt/sdc

Step 13 Run the following command to attach the new partition to the created directory:

mount /dev/xvdb1 Mounting directory

Attaching the newly created partition to the /mnt/sdc directory is used as an example.

mount /dev/xvdb1 /mnt/sdc

Step 14 Run the following command to view the attachment result:

df -TH

Information similar to the following is displayed: (The newly created /dev/xvdb1 partition isattached the /mnt/sdc directory.)

[root@ecs-b656 test]# df -THFilesystem Type Size Used Avail Use% Mounted on/dev/xvda2 xfs 11G 7.4G 3.2G 71% /devtmpfs devtmpfs 4.1G 0 4.1G 0% /devtmpfs tmpfs 4.1G 82k 4.1G 1% /dev/shmtmpfs tmpfs 4.1G 9.2M 4.1G 1% /runtmpfs tmpfs 4.1G 0 4.1G 0% /sys/fs/cgroup/dev/xvda3 xfs 1.1G 39M 1.1G 4% /home/dev/xvda1 xfs 1.1G 131M 915M 13% /boot/dev/xvdb1 ext4 11G 38M 9.9G 1% /mnt/sdc

----End

Setting Automatic Disk Attachment Upon ECS Start

To enable automatic disk attachment when a server starts, you cannot specify /dev/xvdb1in /etc/fstab. This is because the sequence codes of cloud devices may change during theserver stop and start. You are advised to use the universally unique identifier (UUID) to setthe automatic disk attachment.

NOTE

The disk UUID is the unique character string for storage devices in a Linux system.

Step 1 Run the following command to query the disk UUID:

blkid Disk partition

Querying the UUID of /dev/xvdb1 is used as an example:

blkid /dev/xvdb1


[root@ecs-b656 test]# blkid /dev/xvdb1/dev/xvdb1: UUID="1851e23f-1c57-40ab-86bb-5fc5fc606ffa" TYPE="ext4"

Step 2 Run the following command to open the fstab file using the vi editor:

vi /etc/fstab



20

Step 3 Press i to enter the editing mode.

Step 4 Move the cursor to the end of the file and press Enter. Then add the following information:UUID=1851e23f-1c57-40ab-86bb-5fc5fc606ffa /mnt/sdc ext4 defaults 0 2

Step 5 Press Esc, enter :wq, and press Enter.

The system saves the configurations and exits the vi editor.

----End



21

3 Operation Guide

3.1 Managing EVS Disks

3.2 Expanding Capacity of an EVS Disk (Windows)

3.3 Expanding Capacity of an EVS Disk (Linux)

3.4 Backing Up EVS Disks

Elastic Volume ServiceUser Guide 3 Operation Guide


22

3.1 Managing EVS Disks

Attaching an EVS Disk

If you have purchased EVS disks, attach them to servers to be used as data disks. A systemdisk is automatically added to the server upon the server creation, and you do not need tomanually attach the system disk.

You can also create data disks when creating the server, eliminating the subsequent manualattachment. However, if you independently purchase EVS disks, attach the EVS disks toservers. To attach EVS disks, perform the following operations:

Step 1 Log in to the management console.

Step 2 Click . Under Storage, click Elastic Volume Service.

Step 3 Locate the target EVS disk and click Attach.

For details, see Table 3-1.

Table 3-1 Configuration description

EVS Disk Type of AttachedServers

Number ofAttached Servers

Number of ServerMount Points

Non-shared EVSdisk

ECS 1 14

Shared EVS disk 16

Non-shared EVSdisks for whichDevice Type isSCSI

BMS 1 11

Shared EVS disksfor which DeviceType is SCSI

16

Step 4 In the displayed dialog box, select the server to which the disk is to be attached. Select themount point from the drop-down list and click Attach.

The mount point is the drive letter of the EVS disk to be attached to the server. The mountpoint for each EVS disk must be unique on the same server.

Return to the disk list page. If the disk status changes to In-use, the EVS disk is successfullyattached to the server.

Step 5 Initialize the EVS disk.



23

For details, see 2.3 Initializing an EVS Disk (Windows) or 2.4 Initializing an EVS Disk(Linux). The procedure for formatting EVS disks varies depending on the in-use OSs. Fordetails, see the related OS product documentation.

----End

Detaching an EVS Disk

A system disk (mounted on the /dev/sda or /dev/vda mount point) can be detached from theECS only when it is in the Stopped state. Therefore, stop the ECS before detaching systemdisks.

A data disk can be detached from the server when it is in the Stopped or Running state.

Click to unfold detailed information about an EVS disk. Then click the link of the targetserver to view the server status.

On the disk list, locate the row that contains the specified disk and click Detach in theOperation column. If the disk status changes to Available, the disk is successfully detached.

Deleting an EVS Disk

If an EVS disk is no longer used, release virtual resources by deleting the EVS disk from thesystem. A deleted EVS disk is not charged.

Before deleting an EVS disk, ensure that the disk status is Available, Error, Expansionfailed, Restoration failed, or Rollback failed.

For a shared EVS disk, you must detach all the mount points before deleting the disk.

Step 1 In the disk list, locate the row that contains the specified disk, click More in the Operationcolumn, and choose Delete.

Step 2 (Optional) If you need to delete multiple EVS disks, select in front of the target disksand click Delete. In the displayed dialog box, confirm the deletion information and click OK.

----End

NOTICEDeleting an EVS disk deletes all data on the disk. Exercise caution when performing thisoperation.

3.2 Expanding Capacity of an EVS Disk (Windows)

Scenarios

When the available disk space is insufficient, expand the disk capacity with either of thefollowing methods:



24

l Expand the capacity of an existing disk.

l Apply for a new disk and attach it to a server.

Restrictionsl Both the system and data disks support capacity expansion.

l Before expanding EVS disk capacity, ensure that the disk status is Available, that is,EVS disks are not attached to servers. In-use EVS disks cannot be expanded.

Procedure

The method for initializing EVS disks varies depending on the OS in use. This section usesWindows Server 2008 R2 as an example to describe how to initialize an EVS disk. Forinformation about how to initialize EVS disks when other types of Windows OSs are used,see the corresponding OS product documentation.


Step 2 Expand the disk capacity based on the disk type.

l For data disks:

a. Click . Under Storage, click Elastic Volume Service.

b. On the disk list, locate the row that contains the specified disk and click Detach inthe Operation column.

The disk is detached.

c. In the disk list, locate the row that contains the specified disk, click More in theOperation column, and select Expand Capacity.

Enter the size of the newly added disk as prompted.

d. Click Buy Now.

e. Read and agree to the server service agreement.

f. Click Submit Order.

g. Return to the disk list and click to view the disk capacity after modification.After the disk capacity changes to the configured value, the disk capacity issuccessfully expanded.

h. Locate the row that contains the specified disk and click Attach in the Operationcolumn.

The EVS disk is attached to the server.

NOTE

After the disk is successfully attached to the server, you must initialize the disk for the serverto use it.

i. Locate the server that the EVS disk is attached to and log in to the server.

j. On the Server Manager page, select the disk to be expanded. The original diskcapacity is displayed. Figure 3-1 shows the original disk capacity.



25

Figure 3-1 Unallocated disks

k. Right-click the selected disk and select Extend Volume. Figure 3-2 shows the pagefor selecting the extended volume.

Figure 3-2 Selecting the extend volume

l. On the displayed Extend Volume Wizard page, click Next. Figure 3-3 shows theExtend Volume Wizard page.



26

Figure 3-3 Extend volume wizard

m. In the Select Space (MB)(E): row shown in Figure 3-4, enter the target capacityand click Next.

Figure 3-4 Select space

n. Click Finish to complete the wizard. After the capacity expansion is successful, thedisk capacity is greater than the original capacity. Figure 3-5 shows the pagedisplayed after the disk capacity is successful.



27

Figure 3-5 Successful capacity expansion

l For system disks:

a. Log in to the management console.b. On the management console, locate the row that contains the server to which the to-

be-expanded disk is attached.Stop the server.

c. On the disk list, locate the row that contains the specified disk and click Detach inthe Operation column.The disk is detached.

d. In the disk list, locate the row that contains the specified disk, click More in theOperation column, and select Expand Capacity.Enter the size of the newly added disk as prompted.

e. Click Buy Now.f. Read and agree to the server service agreement.g. Click Submit Order.

h. Return to the disk list and click to view the disk capacity after modification.After the disk capacity changes to the configured value, the disk capacity issuccessfully expanded.

i. Locate the row that contains the specified disk and click Attach in the Operationcolumn.The EVS disk is attached to a server.

NOTE


j. Locate the row that contains the server, click More in the Operation column, andselect Start.Start the server.



28

k. Log in to the server.l. On the Server Manager page, select the disk to be expanded. The original disk

capacity is displayed. Figure 3-6 shows the original disk capacity.

Figure 3-6 Selecting the system disk

m. Right-click the selected disk and select Extend Volume. Figure 3-7 shows the pagefor selecting the extended volume.

Figure 3-7 Selecting the extend volume

n. On the displayed Extend Volume Wizard page, click Next. Figure 3-8 shows theExtend Volume Wizard page.



29

Figure 3-8 Extend volume wizard

o. In the Select Space (MB)(E): row shown in Figure 3-9, enter the target capacityand click Next.

Figure 3-9 Select space

p. Click Finish to complete the wizard. After the capacity expansion is successful, thedisk capacity is greater than the original capacity. Figure 3-10 shows the pagedisplayed after the disk capacity is successful.



30

Figure 3-10 Successful capacity expansion

----End

3.3 Expanding Capacity of an EVS Disk (Linux)

Scenarios

When the available disk space is insufficient, expand the disk capacity with either of thefollowing methods:

l Expand the capacity of an existing disk.l Apply for a new disk and attach it to a server.

Restrictionsl Both the system and data disks support capacity expansion.l Before expanding EVS disk capacity, ensure that the disk status is Available, that is, the

EVS disk is not attached to a server. In-use EVS disks cannot be expanded.

Procedure

The method for initializing EVS disks varies depending on the OS in use. This section usesCentOS 7.0 64-bit OS as an example to describe how to initialize an EVS disk when a LinuxOS is used. For information about how to initialize EVS disks when other types of Linux OSsare used, see the corresponding OS product documentation.

For example, an EVS disk has been attached to a Linux server and requires capacityexpansion. The partition is /dev/xvdb1, the mount point is /mnt/sdc, and the file systemformat is ext4.


Step 2 Expand the disk capacity based on the disk type.



31

l For data disks:

a. Locate the server to which the to-be-expanded disk is attached and log in to theserver as user root.

b. Run the following command to detach the disk:umount /mnt/sdc

c. On the management console, locate the row that contains the server to which the to-be-expanded disk is attached.Stop the server.

d. In the navigation tree on the left, click Elastic Volume Service.The EVS disk management page is displayed.

e. Locate the row that contains the target disk and click Detach in the Operationcolumn.The disk is detached.

f. In the disk list, locate the row that contains the specified disk, click More in theOperation column, and select Expand Capacity. Enter the size of the newly addeddisk as prompted.

g. Click Buy Now.h. Read and agree to the server service agreement.i. Click Submit Order.

j. Return to the disk list and click to view the disk capacity after modification.After the disk capacity changes to the configured value, the disk capacity issuccessfully expanded.

k. Locate the row that contains the specified disk and click Attach in the Operationcolumn.The EVS disk is attached to the server.

NOTE


l. Locate the server that the EVS disk is attached to.Start the server.

m. Log in to the server as user root.n. Remotely log in to the server console and run the following command to check the

partition information about the EVS disk:fdisk -lIf information similar to the following is displayed, the server contains twodisks. /dev/xvda is used as the system disk, and /dev/xvdb is the data disk.[root@ecs-b656 test]# fdisk -l


Device Boot Start End Blocks Id System



32

/dev/xvda1 * 2048 2050047 1024000 83 Linux/dev/xvda2 2050048 22530047 10240000 83 Linux/dev/xvda3 22530048 24578047 1024000 83 Linux/dev/xvda4 24578048 83886079 29654016 5 Extended/dev/xvda5 24580096 26628095 1024000 82 Linux swap / Solaris


Device Boot Start End Blocks Id System/dev/xvdb1 2048 20971519 10484736 83 LinuxCapacity of the /dev/xvdb disk is successfully expanded.

NOTE

After the disk capacity is successfully expanded, use the disk, such as how the disk ispartitioned and to which directory the disk is attached, based on your requirements. Thisdocument only provides an example.

o. Run the following command and enter d to delete the /dev/xvdb1 existing partition:fdisk /dev/xvdbInformation similar to the following is displayed:[root@ecs-b656 test]# fdisk /dev/xvdbWelcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.Be careful before using the write command.

Command (m for help): dSelected partition 1Partition 1 is deleted

Command (m for help):p. Enter n and press Enter to create partitions.

Enter n to add a partition.Information similar to the following is displayed:n p indicates the primary partition.n e indicates the extended partition.Command (m for help): nPartition type: p primary (0 primary, 0 extended, 4 free) e extended

q. Enter p and press Enter to create a primary partition as an example.Information similar to the following is displayed: (Partition number indicates theserial number of the primary partition. The value can be 1 to 4.)Select (default p): pPartition number (1-4, default 1):

r. Enter the number of the primary partition and press Enter. Primary partitionnumber 1 is used as an example.Information similar to the following is displayed: (First sector indicates the startcylinder number. The value can be 2048 to 20971519, and the default value is2048.)Partition number (1-4, default 1): 1First sector (2048-20971519, default 2048):



33

s. Select the default start cylinder number 2048 and press Enter.Information similar to the following is displayed: (Last sector indicates the endcylinder number. The value can be 2048 to 20971519, and the default value is20971519.)First sector (2048-20971519, default 2048):Using default value 2048Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519):

t. Select the default end cylinder number 20971519 and press Enter.Information similar to the following is displayed: (The partition is successfullycreated.)Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519):Using default value 20971519Partition 1 of type Linux and of size 10 GiB is setCommand (m for help):

u. Enter p and press Enter to view the created partition.Information similar to the following is displayed: (Details about the /dev/xvdb1partition are displayed.)Command (m for help): p


Device Boot Start End Blocks Id System/dev/xvdb1 2048 20971519 10484736 83 Linux


v. Enter w and press Enter to write the partition result to the partition table.Information similar to the following is displayed: (The partition is successfullycreated.)Command (m for help): wThe partition table has been altered!

Calling ioctl() to re-read partition table.Syncing disks.

w. Run the following commands to check and adjust the size of the /dev/xvde1partition:e2fsck -f /dev/xvdb1Information similar to the following is displayed:[root@ecs-b656 test]# e2fsck -f /dev/xvdb1e2fsck 1.42.9 (28-Dec-2013)Pass 1: Checking inodes, blocks, and sizesPass 2: Checking directory structurePass 3: Checking directory connectivityPass 4: Checking reference countsPass 5: Checking group summary information/dev/xvdb1: 11/655360 files (0.0% non-contiguous), 83137/2621184 blocks

resize2fs /dev/xvdb1Information similar to the following is displayed:[root@ecs-b656 test]# resize2fs /dev/xvdb1resize2fs 1.42.9 (28-Dec-2013)Resizing the filesystem on /dev/xvdb1 to 6029056 (4k) blocks.The filesystem on /dev/xvdb1 is now 6029056 blocks long.



34

l For system disks:

a. On the management console, locate the row that contains the server to which the to-be-expanded disk is attached.Stop the server.

b. In the navigation tree on the left, click Elastic Volume Service.The EVS disk management page is displayed.

c. Locate the row that contains the target disk and click Detach in the Operationcolumn.The disk is detached.

d. Click Buy Now.e. Read and agree to the server service agreement.f. Click Submit Order.

g. Return to the disk list and click to view the disk capacity after modification.After the disk capacity changes to the configured value, the disk capacity issuccessfully expanded.

h. Locate the row that contains the specified disk and click Attach in the Operationcolumn.The EVS disk is attached to the server.

NOTE


i. Locate the server that the EVS disk is attached to.Start the server.

j. Log in to the server as user root.k. Run the following command to view the disk information:

fdisk -lInformation similar to the following is displayed: (/dev/xvda indicates the systemdisk.)[root@ecs-bab9 test]# fdisk -l


Device Boot Start End Blocks Id System/dev/xvda1 * 2048 2050047 1024000 83 Linux/dev/xvda2 2050048 22530047 10240000 83 Linux/dev/xvda3 22530048 24578047 1024000 83 Linux/dev/xvda4 24578048 83886079 29654016 5 Extended/dev/xvda5 24580096 26628095 1024000 82 Linux swap / Solaris

NOTE

If the to-be-expanded disk is a system disk, enable the target partition to be automaticallyattached upon system startup. Otherwise, the expanded data is not displayed.



35

The following steps use an example to describe how to create a new partition for theexpanded disk space and attach the partition to the /opt directory.

l. Run the following command to enter the fdisk mode (/dev/xvda is used as anexample):fdisk /dev/xvdaInformation similar to the following is displayed:[root@ecs-bab9 test]# fdisk /dev/xvdaWelcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.Be careful before using the write command.

Command (m for help):m. Enter n and press Enter to create partitions.

Because the system disk has five existing partitions, the system automaticallycreates a sixth one.Information similar to the following is displayed:Command (m for help): nAll primary partitions are in useAdding logical partition 6First sector (26630144-83886079, default 26630144):

n. Enter the start cylinder number, for example, the default number, and press Enter.The start cylinder number must be greater than the end cylinder number of theexisting partition.Information similar to the following is displayed:First sector (26630144-83886079, default 26630144):Using default value 26630144Last sector, +sectors or +size{K,M,G} (26630144-83886079, default 83886079):

o. Enter the new partition's end cylinder number and press Enter.The default end cylinder number is used as an example.Information similar to the following is displayed:Last sector, +sectors or +size{K,M,G} (26630144-83886079, default 83886079):Using default value 83886079Partition 6 of type Linux and of size 27.3 GiB is set

Command (m for help): p. Enter p and press Enter to view the created partition.

Information similar to the following is displayed:Disk /dev/xvda: 64.4 GB, 64424509440 bytes, 125829120 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk label type: dosDisk identifier: 0x000cc4ad

Device Boot Start End Blocks Id System/dev/xvda1 * 2048 2050047 1024000 83 Linux/dev/xvda2 2050048 22530047 10240000 83 Linux/dev/xvda3 22530048 24578047 1024000 83 Linux/dev/xvda4 24578048 83886079 29654016 5 Extended/dev/xvda5 24580096 26628095 1024000 82 Linux swap / Solaris/dev/xvda6 26630144 83886079 28627968 83 Linux




36

q. Enter w and press Enter.Enter the partition result into the partition table to complete partition creation.Information similar to the following is displayed:Command (m for help): wThe partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.The kernel still uses the old table. The new table will be used atthe next reboot or after you run partprobe(8) or kpartx(8)Syncing disks.

r. Run the following command to synchronize the new partition table to the disk:partprobe

s. Run the following command to set the format for the file system of the newlycreated partition:mkfs -t ext4 /dev/xvda6Take the ext4 file format as an example. After a period of time, observe the systemrunning status. Information similar to the following is displayed:[root@ecs-bab9 test]# mkfs -t ext4 /dev/xvda6mke2fs 1.42.9 (28-Dec-2013)Filesystem label=OS type: LinuxBlock size=4096 (log=2)Fragment size=4096 (log=2)Stride=0 blocks, Stripe width=0 blocks1790544 inodes, 7156992 blocks357849 blocks (5.00%) reserved for the super userFirst data block=0Maximum filesystem blocks=2155872256219 block groups32768 blocks per group, 32768 fragments per group8176 inodes per groupSuperblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000

Allocating group tables: doneWriting inode tables: doneCreating journal (32768 blocks): doneWriting superblocks and filesystem accounting information: done

t. Run the following command to attach the new partition to the directory whosespace needs to be added (for example, /opt):mount /dev/xvda6 /optInformation similar to the following is displayed:[root@ecs-bab9 test]# mount /dev/xvda6 /opt[root@ecs-bab9 test]#

NOTE

If the new partition is attached to a directory that is not empty, the subdirectories and files inthe directory will be hidden. Therefore, you are advised to attach the new partition to anempty directory or a newly created directory. If the new partition must be attached to adirectory that is not empty, move the subdirectories and files in the directory to anotherdirectory temporarily. After the partition is successfully attached to the directory, move thesubdirectories and files back.

u. Run the following command to view the attachment result:



37

df -THInformation similar to the following is displayed:[root@ecs-bab9 test]# df -THFilesystem Type Size Used Avail Use% Mounted on/dev/xvda2 xfs 11G 7.4G 3.2G 71% /devtmpfs devtmpfs 4.1G 0 4.1G 0% /devtmpfs tmpfs 4.1G 82k 4.1G 1% /dev/shmtmpfs tmpfs 4.1G 9.2M 4.1G 1% /runtmpfs tmpfs 4.1G 0 4.1G 0% /sys/fs/cgroup/dev/xvda3 xfs 1.1G 39M 1.1G 4% /home/dev/xvda1 xfs 1.1G 131M 915M 13% /boot/dev/xvda6 ext4 29G 47M 28G 1% /opt

----End

3.4 Backing Up EVS Disks

Scenarios

After VBS is enabled, you can back up EVS disk data. For details, see section Creating aVBS Backup in the Volume Backup Service User Guide.

NOTE

You can create backups only when the EVS disks are in the Available or In-use state.

You cannot create EVS disk backups if your account balance is less than 100 RMB or your account isfrozen.

Configuring a Backup Policy

With backup policies configured, data in EVS disks can be periodically backed up to improvethe data security.


Step 2 Click . Under Storage, click Elastic Volume Service.

Step 3 In the disk list, locate the EVS disk whose data you want to back up and choose More >Configure Backup Policy in the Operation column.

The Configure Backup Policy dialog box is displayed.

Step 4 In the list of backup policies, click Associate to select the target backup policy.

NOTE

If the EVS disk has been associated with a backup policy, you can first disassociate the EVS disk withthis backup policy and then associate it with the target one.

Step 5 (Optional) To create a new backup policy, click Edit Backup Policy.

The Volume Backup Service page is displayed.

For details about how to create a backup policy, see section Data Backup Using a BackupPolicy in the Volume Backup Service User Guide.

Step 6 In the displayed Associate Backup Policy dialog box, click OK.



38

http://support.hwclouds.com/usermanual/vbs/en-us_topic_0015667820.html

http://support.hwclouds.com/usermanual/vbs/en-us_topic_0015667820.html

http://support.hwclouds.com/en-us/usermanual-vbs/en-us_topic_0033745918.html

http://support.hwclouds.com/en-us/usermanual-vbs/en-us_topic_0033745918.html

After the association is complete, the system automatically backs up data in EVS disksaccording to the backup policy.

----End



39

4 FAQs

4.1 What Is Elastic Volume Service?

4.2 What Are the Types of EVS Disks?

4.3 What Are EVS Disk Specifications?

4.4 How Is the EVS Disk Performance?

4.5 How Many EVS Disks Can Be Attached to a Server?

4.6 Can I Attach an EVS Disk to Multiple Servers?

4.7 How Can I Attach an EVS Disk to a Server?

4.8 Can EVS Disk Capacity Be Changed?

4.9 Is Disk Capacity Expansion Supported?

4.10 How Can I Expand EVS Disk Capacity?

4.11 How Many EVS Disks Can I Purchase?

4.12 Will Data in the EVS Disk Be Lost When the EVS Disk Is Detached?

4.13 How Many Status Types Does an EVS Disk Have? What Does Each Status Type Mean?

4.14 What Should I Do If an Error Occurs on My EVS Disk?

4.15 What Are the ECS Types Supported by EVS Disks for Which Device Type Is SCSI?

4.16 What Is a Shared EVS Disk?

Elastic Volume ServiceUser Guide 4 FAQs


40

4.1 What Is Elastic Volume Service?Elastic Volume Service (EVS) disks are scalable virtual block storage devices designedbased on the distributed architecture. You can create EVS disks online and attach them toservers. A server can be an Elastic Cloud Server (ECS) or a Bare Metal Server (BMS). Themethod for using EVS disks is the same as that for using hard disks on physical servers.Compared with traditional hard disks, EVS disks have higher data reliability and I/Othroughput capabilities. They are also easier to use. EVS disks apply to file systems,databases, and system software and applications that require block storage devices.

EVS disks are also called disks.

4.2 What Are the Types of EVS Disks?Three types of EVS disks are provided: ultra-high I/O, high I/O, and common I/O.

EVS disks with different I/O capacities provide different features at different prices. ChooseEVS disks based on your requirements.

l EVS disks with ultra-high I/O

EVS disks that use solid state disk (SSD). These EVS disks provide ultra-high I/O andlow latency. They support NoSQL, RDS, and data warehouse applications.

l EVS disks with high I/O

EVS disks that use serial attached SCSI (SAS). These EVS disks provide high I/O andlow latency. They support RDS, NoSQL, data warehouse, and file system applications.

l EVS with common I/O

EVS disks that use Serial Advanced Technology Attachment (SATA). These EVS disksprovide reliable block storage and can run key applications.

4.3 What Are EVS Disk Specifications?EVS disks can meet large-capacity storage requirements. The capacity of system disks rangesfrom 40 GB to 32768 GB, and that of data disks ranges from 100 GB to 32768 GB.

4.4 How Is the EVS Disk Performance?Table 4-1 lists the EVS disk performance.

Table 4-1 Performance data of the EVS disk

Parameter Common I/O High I/O Ultra-high I/O

Maximum capacity of adisk

32 TB 32 TB 32 TB

Maximum IOPS of adisk

1000 3000 20000



41



http://www.hwclouds.com/product/rds.html

http://www.hwclouds.com/en-us/product/rds.html

http://www.hwclouds.com/en-us/product/evs.html

http://www.hwclouds.com/en-us/product/evs.html

Parameter Common I/O High I/O Ultra-high I/O

Maximum throughput ofa disk

90 MBPS 150 MBPS 350 MBPS

Delay 10 ms 3 ms 2 ms

4.5 How Many EVS Disks Can Be Attached to a Server?Up to 10 EVS disks can be attached to a server.

4.6 Can I Attach an EVS Disk to Multiple Servers?An EVS disk can be attached to only one server.

A shared EVS disk can be attached to a maximum of 16 servers.

4.7 How Can I Attach an EVS Disk to a Server?Log in to the management console, locate the row that contains the target disk, and clickAttach in the Operation column.

4.8 Can EVS Disk Capacity Be Changed?Yes. However, it can only be expanded.

4.9 Is Disk Capacity Expansion Supported?EVS disks, including data and system disks, support capacity expansion.

You can expand the EVS disk capacity only when the disk is available, that is, not mounted toa server. Capacity of disks in the In-use state cannot be expanded.

Figure 4-1 shows the disk status.

Figure 4-1 Disk status

4.10 How Can I Expand EVS Disk Capacity?The process for expanding the disk capacity is as follows:

1. Detaching the EVS disk: Detach the disk from the server.



42

2. Expanding the EVS disk capacity: Expand the capacity of the disk.3. Attaching the EVS disk: Attach the expanded disk to the server.4. Initializing the EVS disk: Log in to the server and initialize the expanded EVS disk. You

can use the expanded EVS disk after the initialization is complete.

For details, see Expanding Capacity of an EVS Disk (Windows) and Expanding Capacityof an EVS Disk (Linux) in the Elastic Volume Service User Guide.

4.11 How Many EVS Disks Can I Purchase?You can purchase up to 100 EVS disks.

4.12 Will Data in the EVS Disk Be Lost When the EVSDisk Is Detached?

Not necessarily.

To prevent data loss when you detach an EVS disk, perform the following operations:

l For Windows OSs, stop the server and perform the disk detachment operations on themanagement console.

l For Linux OSs, log in to the server and run the umount command to detach the EVSdisk. After the command is successfully executed, stop the server and perform the diskdetachment operations on the management console.

4.13 How Many Status Types Does an EVS Disk Have?What Does Each Status Type Mean?

An EVS disk has several status types. The following table lists the EVS disk status, themeaning of each status, and the operations a disk in each status allows.

Table 4-2 EVS disk status description

EVS DiskStatus

Description Allowed Operation

In-use The EVS disk is attached to a server and is inuse.

l Detachingl Creating VBS

backupsNOTE

If a shared EVS diskis in the In-use state,the disk can beattached.



43

EVS DiskStatus


Available The EVS disk has not been attached to anyserver and can be attached.

l Attachingl Expandingl Deletingl Creating VBS

backupsl Rolling back a

snapshot to an EVSdisk. For details, seeEVS Snapshot >Rolling Back aSnapshot to an EVSDisk in the ElasticVolume Service APIReference.

Creating The EVS disk is being created. None

Attaching The EVS disk is being attached to a server. None

Detaching The EVS disk is being detached from a server. None

Deleting The EVS disk is being deleted. None

Restoring A VBS backup is being used to restore theEVS disk.

None

Expanding The capacity of the EVS disk is beingexpanded.

None

Uploading Data on the EVS disk is being uploaded to animage. This state occurs when you create animage from a server.

None

Downloading Data is being downloaded from an image tothe EVS disk. This state occurs when youcreate a server.

None

Error An error occurs when you try to create anEVS disk.

Deleting

Deletion failed An error occurs when you try to delete anEVS disk.

No operations can beperformed.

Expansionfailed

An error occurs when you try to expand thecapacity of an EVS disk.

Deleting

Restorationfailed

An error occurs when you try to restore anEVS disk from a backup.

Deleting



44

EVS DiskStatus


Rolling back Data on the EVS disk is being restored from asnapshot.NOTE

l When you roll back a snapshot to an EVS disk,you can restore only the disk to the source EVSdisk. Rollback to specified disks is notsupported.

l You can roll back an EVS disk from a snapshotonly when the disk is in the Available orRollback failed state.

None

Rollbackfailed

An error occurs when an EVS disk is rolledback from a snapshot.

l Deletingl Rolling back a

snapshot to an EVSdisk. For details, seeEVS Snapshot >Rolling Back aSnapshot to an EVSDisk in the ElasticVolume Service APIReference.

NOTE

If an EVS disk status is Error, Deletion failed, Expansion failed, Restoration failed, or Rollbackfailed, you can rectify the error by following the steps provided in section 4.14 What Should I Do If anError Occurs on My EVS Disk?.

4.14 What Should I Do If an Error Occurs on My EVSDisk?

If an error occurs, the disk may show one of the states listed in the following table. Accordingto the error status, attempt the suggested solution.

Table 4-3 Solutions for disk errors

ErrorStatus

Handling Suggestion

Error Delete the EVS disk in the Error state and create another one.If you select Yearly/Monthly to create the disk and an error occurs duringdisk creation, customer service personnel will help you handle the error. Ifyou require that the error be handled as soon as possible, contact ourcustomer service personnel.



45

ErrorStatus

Handling Suggestion

Deletionfailed

Contact customer service personnel.The disk will no longer be charged once its status changes to Deletionfailed.

Expansionfailed

Our customer service personnel will contact you and help you handle thiserror. Do not perform any operations on the disk before the customer servicepersonnel contact you. If you require that the error be handled as soon aspossible, contact our customer service personnel.

Restorationfailed

Our customer service personnel will contact you and help you handle thiserror. Do not perform any operations on the disk before the customer servicepersonnel contact you. If you require that the error be handled as soon aspossible, contact our customer service personnel.

Rollbackfailed

Roll back the snapshot to the EVS disk again. For details, see EVSSnapshot > Rolling Back a Snapshot to an EVS Disk in the ElasticVolume Service API Reference.

4.15 What Are the ECS Types Supported by EVS Disks forWhich Device Type Is SCSI?

The default device type of an EVS disk is Virtual Block Device (VBD), which supports onlybasic SCSI read and write commands. If SCSI is selected for Device Type, the created EVSdisk supports transparent SCSI command transmission and the system allows the server OS todirectly access underlying storage media. EVS disks for which Device Type is SCSI supportboth basic and advanced SCSI commands.

EVS disks for which Device Type is SCSI support the following OS images:

l ECSs running the Windows system support the following public images:– Windows 2008 R2 Standard 64bit English– Windows 2012 R2 Datacenter English– Windows 2012 R2 Datacenter– Windows 2012 R2 Standard English– Windows 2012 R2 Standard– Windows Server Datacenter 2008 R2 64bit– Windows Server Enterprise 2008 R2 64bit English– Windows Server Enterprise 2008 R2 64bit– Windows Server Enterprise 2008 SP2 64bit– Windows Server Standard 2008 R2 64bit– Windows Web Server 2008 R2 64bit

l ECSs running the Linux system support the following private images:– Novell SUSE Linux Enterprise Server 11 SP4 64bit (The kernel version is

3.0.101-68-default or 3.0.101-80-default.)



46

– Novell SUSE Linux Enterprise Server 12 64bit (The kernel version is3.12.51-52.31-default.)

– Novell SUSE Linux Enterprise Server 12 SP1 64bit (The kernel version is3.12.67-60.64.24-default.)

NOTICETo use EVS disks for which Device Type is SCSI, ECSs running the Linux systemsupport only the preceding private images and require the Paravirtual SCSI(PVSCSI) driver installed. You can download source code from https://github.com/UVP-Tools/SAP-HANA-Tools and compile the source code to obtainthe driver.

4.16 What Is a Shared EVS Disk?

Introduction

Shared EVS disks are block storage devices that support concurrent read and write operationsand can be attached to multiple servers. Shared EVS disks feature multi-mount points, high-concurrency, high-performance, and high-reliability. A shared EVS disk can be attached to amaximum of 16 servers.

Figure 4-2 shows the application scenario of shared EVS disks.

Figure 4-2 Application scenario of shared EVS disks

You can create shared EVS disks for which Device Type is set to either VBD or SCSI.



47

https://github.com/UVP-Tools/SAP-HANA-Tools

https://github.com/UVP-Tools/SAP-HANA-Tools

l Shared EVS disks for which Device Type is VBD: The device type of newly createdshared EVS disks is VBD by default. Such disks can be used as virtual block storagedevices, but do not support SCSI reservations. If SCSI reservations are required for yourapplication deployment, create shared EVS disks for which Device Type is SCSI.

l Shared EVS disks for which Device Type is SCSI: These EVS disks support SCSIreservations.

If shared EVS disks for which Device Type is SCSI are attached to an ECS, SCSIreservations take effect only when such disks are used together with the anti-affinitypolicy of an ECS group.

NOTICETo improve data security, you are advised to use SCSI reservations together with theanti-affinity policy of an ECS group. Shared EVS disks for which Device Type is SCSIcan be attached to ECSs in the same ECS group. Do not attach such EVS disks to ECSsnot belonging to any ECS group. Otherwise, SCSI reservations may not work properly,which may put data at risk.

NOTE

l The anti-affinity policy of an ECS group allows you to create ECSs on different hosts, therebyimproving service reliability. This function does not apply to existing ECSs. You cannot addexisting ECSs to an ECS group.

For details about ECS groups, see section (Optional) Creating an ECS Group in the ElasticCloud Server User Guide.

l The SCSI reservation mechanism uses a SCSI Reservation command to perform SCSIreservation operations. If an ECS sends such a command to an EVS disk, the disk displayed aslocked to other ECSs, preventing the data damage that may be caused by simultaneous readand write operations to the disk from multiple ECSs.

l Relationship between ECS groups and SCSI reservations: SCSI reservation on a single EVSdisk cannot differentiate multiple ECSs on the same physical host. In this case, SCSIreservations are supported only when ECSs belong to different physical hosts. Servers belongto the same physical host but not the same anti-affinity ECS group also do not support SCSIreservation. In this case, you are advised to use SCSI reservation command together with theanti-affinity policy of an ECS group.

Characteristicsl Multi-mount points: A shared EVS disk can be attached to a maximum of 16 servers.

l High-performance: When multiple servers concurrently access an ultra-high I/O sharedEVS disk, random read and write IOPS can reach a maximum of 160000.

l High-reliability: Shared EVS disks support both manual and automatic backup,delivering 99.9999999% data reliability.

l Wide range of application scenarios: Shared EVS disks can apply to the Oracle RACscenario where only disks of the VBD device type are needed. Whereas, they can alsoapply to Windows MSCS and Veritas VCS scenarios that require SCSI commands.

l Host isolation: Shared EVS disks support the anti-affinity policy, which ensures thatservers with the cluster application deployed are located on different physical servers.



48

SpecificationsTable 4-4 lists the currently supported specifications of shared EVS disks.

Table 4-4 Specifications of shared EVS disks

Name Common I/O High I/O Ultra-high I/O

Maximum capacity of a singledisk

32 TB 32 TB 32 TB

Random read and write IOPS > 8000 > 20000 > 160000

Latency of read and write I/O 10 ms 3 ms 1 ms

Random read and writethroughput

> 300 MByte/s > 1 GByte/s > 2 GByte/s

Estimated price The shared EVS disk feature is in beta testing, and userscan use it for free.

Data reliability 99.9999999%

Number of servers that can beattached to

A shared EVS disk can be attached to a maximum of 16server.

NOTE

Maximum IOPS and maximum throughput must be measured under the circumstance that multipleservers are concurrently using a shared EVS disk.

Application ScenariosShared EVS disks mainly apply to enterprise key applications that require cluster deploymentand high availability (HA). These applications are based on the share-everything architectureand require concurrent access to an EVS disk from multiple servers. Example applicationsinclude Oracle RAC, Windows MSCS, Linux RHCS, Veritas VCS, and Veritas CFS.

Application ScenariosSame as traditional storage devices, shared EVS disks provide shared block storage devicesfor servers. However, the shared EVS disk itself does not provide cluster capabilities, andusers need to deploy a cluster system to manage shared EVS disks.

If you attach a shared EVS disk to multiple servers, determine first the device type for thedisk. Shared EVS disk for which Device Type is SCSI supports SCSI reservations. Beforeusing SCSI reservations, users need to install the driver in the server OS and ensure that thein-use image is within the compatibility list.

If a shared EVS disk is used but SCSI reservation is not enabled, the following issues mayoccur:l Storage space allocation conflict

When a shared EVS disk is attached to multiple servers, they are not aware of the storagespace size allocated to other servers. In this case, storage spaces may be repeatedlyallocated, causing an allocation conflict.



49

l Storage data inconsistencyIf SCSI is selected for Device Type, the created EVS disk supports transparent SCSIcommand transmission and the system allows the server OS to directly access underlyingstorage media. If SCSI reservation is not enabled, a server caches the data. In this case,the data is not available on other servers, and the data read from different servers areinconsistent. Also, if such data is modified by other servers, the data after modificationoverwrite the original data, and data inconsistency occurs.



50

A Change History

ReleaseDate

What's New

2017-04-22 This issue is the sixth official release, which incorporates the followingchanges:l Added EVS disks for which Device Type is SCSI.l Added support for shared EVS disks.

2017-03-30 This issue is the fifth official release, which incorporates the followingchange:l Added the Rolling back and Rollback failed states for EVS disks.

2016-12-30 This issue is the fourth official release, which incorporates the followingchanges:l Modified the flow chart in section 2.1 Operation Procedure.l Modified the operations for initializing data disks in section 2.4

Initializing an EVS Disk (Linux).

2016-11-30 This issue is the third official release, which incorporates the followingchanges:l Added section 2.1 Operation Procedure.l Updated the command output information in sections 2.3 Initializing

an EVS Disk (Windows), 2.4 Initializing an EVS Disk (Linux), 3.2Expanding Capacity of an EVS Disk (Windows), and 3.3Expanding Capacity of an EVS Disk (Linux).

l Divided the previous section "EVS Disk Capacity Expansion" into twonew sections, 3.2 Expanding Capacity of an EVS Disk (Windows)and 3.3 Expanding Capacity of an EVS Disk (Linux).

2016-07-15 This issue is the second official release, which incorporates the followingchange:l Modified the description for attaching EVS disks in section 2.3

Initializing an EVS Disk (Windows).

2016-03-14 This issue is the first official release.

Elastic Volume ServiceUser Guide A Change History


51

User Guide - static.huaweicloud.com · HUAWEI TECHNOLOGIES CO., LTD. ... l Expand the capacity of an EVS disk. l Create an EVS disk backup. ... lists the EVS monitoring metrics.

Documents