Data storage management and retrieval

8/13/2019 Data storage management and retrieval

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Section ObjectiveUpon completion of this section, you will be able to: Understand the concept of information availability

and its measurement

Describe the backup/recovery purposes andconsiderations

Discuss architecture and different backup/recoverytopologies

Describe local replication technologies and theiroperation Describe remote replication technologies and their

operation.

Introduction to Business Continuity - 2


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Chapter ObjectiveAfter completing this chapter, you will be able to:

Define Business Continuity and Information Availability

Detail impact of information unavailability Define BC measurement and terminologies

Describe BC planning process

Detail BC technology solutions



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What isBusiness Continuity Business Continuity is preparing for, responding to,

and recovering from an application outage thatadversely affects business operations

Business Continuity solutions address unavailabilityand degraded application performance

BC is an integrated and enterprise wide process and set

of activities to ensure information availability



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What is Information Availability

(IA) IA refers to the ability of an infrastructure to function

according to business expectations during its specifiedtime of operation

IA can be defined in terms of three parameters: Accessibility

Information should be accessible at right place and to theright user

Reliability Information should be reliable and correct

Timeliness Information must be available whenever required



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Causes of Information Unavailability

Introduction to Business Continuit

Disaster (


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Impact of Downtime


Lost RevenueKnow the downtime costs (perhour, day, two days...) Number of employees

impacted (x hours out *

hourly rate)

Damaged Reputation

Customers

Suppliers

Financial markets

Banks

Business partners

Financial Performance

Revenue recognition

Cash flow

Lost discounts (A/P)

Payment guarantees

Credit ratingStock price

Other Expenses

Temporary employees, equipment rental, overtime

costs, extra shipping costs, travel expenses...

Direct loss

Compensatory payments

Lost future revenue

Billing losses

Investment losses

Lost Productivity


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Measuring Information Availability

MTBF:Average time available for a system or component to perform itsnormal operations between failures

MTTR:Average time required to repair a failed component

IA = MTBF / (MTBF + MTTR) or IA = uptime / (uptime +

downtime)Introduction to Business Continuit

Detection

IncidentTime

Detectionelapsed

time

Diagnosis

Response Time

Repair

Recovery

Repair time

Restoration

Recovery Time

MTTRTime to repair or downtime

Incident

MTBFTime betweenfailures or uptime


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Availability MeasurementLevels of 9s Availability

% Uptime % Downtime Downtime per Year Downtime per Week

98% 2% 7.3 days 3hrs 22 min

99% 1% 3.65 days 1 hr 41 min

99.8% 0.2% 17 hrs 31 min 20 min 10 sec

99.9% 0.1% 8 hrs 45 min 10 min 5 sec

99.99% 0.01% 52.5 min 1 min

99.999% 0.001% 5.25 min 6 sec

99.9999% 0.0001% 31.5 sec 0.6 sec

Introduction to Business Continuit


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BC Terminologies Disaster recovery

Coordinated process of restoring systems, data, andinfrastructure required to support ongoing business

operations in the event of a disaster Restoring previous copy of data and applying logs to that

copy to bring it to a known point of consistency

Generally implies use of backup technology

Disaster restart Process of restarting from disaster using mirrored

consistent copies of data and applications

Generally implies use of replication technologies



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BC Terminologies (Cont.)Recovery Point Objective (RPO)

Point in time to which systemsand data must be recovered afteran outage

Amount of data loss that a

business can endure

Recovery Time Objective (RTO)

Time within which systems,applications, or functions mustbe recovered after an outage

Amount of downtime that a

business can endure and survive

Introduction to Business Continuity - 12Recovery-point objective Recovery-time objective

Seconds

Minutes

Hours

Days

Weeks

Seconds

Minutes

Hours

Days

Weeks Tape Backup

Periodic Replication

Asynchronous Replication

Synchronous Replication

Tape Restore

Disk Restore

Manual Migration

Global Cluster


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Business Continuity Planning (BCP)

Process Identifying the critical business functions

Collecting data on various business processes within

those functions Business Impact Analysis (BIA)

Risk Analysis

Assessing, prioritizing, mitigating, and managing risk

Designing and developing contingency plans anddisaster recovery plan (DR Plan)

Testing, training and maintenance



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BC Technology Solutions Following are the solutions and supporting

technologies that enable business continuity anduninterrupted data availability:

Single point of failure

Multi-pathing software

Backup and replication

Backup recovery Local replication

Remote replication



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Reso lv ing Sing le Points of Failure

FC Switches

Storage Array

Redundant Network

Clustered ServersRedundant Arrays

Remote Site

Redundant Ports

Redundant FC Switches

Redundant Paths

Heartbeat Connection

IP

Storage Array

Client


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Multi-pathing Software Configuration of multiple paths increases data

availability

Even with multiple paths, if a path fails I/O will notreroute unless system recognizes that it has analternate path

Multi-pathing software helps to recognize and utilizes

alternate I/O path to data Multi-pathing software also provide the load balancing

Load balancing improves I/O performance and datapath utilization



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Backup and Replication Local Replication

Data from the production devices is copied to replica deviceswithin the same array

The replicas can then be used for restore operations in the

event of data corruption or other events Remote Replication

Data from the production devices is copied to replica deviceson a remote array

In the event of a failure, applications can continue to run fromthe target device

Backup/Restore Backup to tape has been a predominant method to ensure

business continuity Frequency of backup is depend on RPO/RTO requirements



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Chapter SummaryKey points covered in this chapter:

Importance of Business Continuity

Types of outages and their impact to businesses Information availability measurements

Definitions of disaster recovery and restart, RPO andRTO

Business Continuity technology solutions overview



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Concept in PracticeEMC PowerPath


SE

RVER

STORAGE

SCSI

Driver

SCSI

Driver

SCSI

Driver

SCSI

Driver

SCSI

Driver

SCSI

Driver

SCSI

Controller

SCSI

Controller

SCSI

Controller

SCSI

Controller

SCSI

Controller

SCSI

Controller

PowerPath Host Based Software

Resides between

application and SCSI

device driver

Provides Intelligent I/O

path management

Transparent to the

application

Automatic detection

and recovery from

host-to-array path

failures

Host Application (s)

LUNLUN

LUNLUN

Storage Network


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Check Your Knowledge Which concerns do business continuity solutions address?

Availability is expressed in terms of 9s. Explain therelevance of the use of 9s for availability, using examples.

What is the difference between RPO and RTO? What is the difference between Disaster Recovery and

Disaster Restart?

Provide examples of planned and unplanned downtime in

the context of storage infrastructure operations. What are some of the Single Points of Failure in a typical

data center environment?



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System Management


Management systems in storage networks

Five basic services

Different service interface


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System Management


Requirements

User related

Component related

Architecture related


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System Management


Requirements

User related

Network administrator

Data transport functions properly

transmission capacity and protocols

Storage administrator

Allocation of LUNs to the server

RAID configuration

Industrialist economist

Wear and tear of devices

Related cost

Balanced management:

Conception of network

Implement of storage network

Easier management


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System Management


Requirements

Component related

Applications: These include all software that processes data in a

storage network.

Data: Data is the term used for all information that is processed by the

applications, transported over the network and stored on storage

resources.

Resources: The resources include all the hardware that is required for

the storage and the transport of the data and the operation of

applications.

Network: The term network is used to mean the connections between

the individual resources.

Individual component requirement: monitoring, availability, performance

or scalability.


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System Management


Requirements

Architecture related

servers and storage devices are decoupled by multiple virtualization

layers

assignment of storage capacity to servers

application will be impacted by maintenance.

host bus adapters, hubs, switches, gateways can each affect the data

flow.

Solution: Central management system


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System Management


Basic Services

Discovery

Monitoring

Central configuration

Analysis

Data management


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System Management


The discovery component detects the applications and resources

used in the storage network automatically.

It collects information about the properties, the current

configuration and the status of resources. The status comprises

performance and error statistics.

It correlates and evaluates all gathered information and supplies

the data for the representation of the network topology.


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System Management


The monitoring component compares continuously the current

state of applications and resources with their target state.

In the event of an application crash or the failure of a resource, it

must take appropriate measures to raise the alert based upon the

severity of the error that has occurred.

The monitoring components performs error isolation by trying to

find the actual cause of the fault in the event of the failure of part

of the storage network


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System Management


The central configuration component significantly simplifies the

configuration of all components.

For instance, the zoning of a switch and the LUN masking of a

disk subsystem for the setup of a new server can be configured

centrally where in the past the usage of isolated tools was

required.

Only a central management system can help the administrator to

coordinate and validate the single steps.

Furthermore it is desired to simulated the effects of potential

configuration changes in advance before the real changes areexecuted.


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System Management


The analysis component collects continuously current

performance statistics, error statistics and configuration

parameters and stores them in a data warehouse.

These historic data enables trend analysis to determine capacity

limits in advance to plan necessary expansions on time. This

supports operational as well as economic conclusions.

An further aspect is the spotting of error-prone components and

the detection of single point of failures.


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System Management


The data management component covers all aspects regarding

the data such as performance, backup, archiving and migration

and controls the efficient utilization and availability of data and

resources.

The administrator can define policies to control the placement

and the flow of the data automatically.


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System Management


Characteristics of Management

interfaces:

There are two main types of

device in the storage network:

connection devicesend-point devices.

Types of interfaces:

In-band

Out- band

Standardized

Proprietary


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System Management


In-bandInterfaces for the management of end-point devices

Management functions for discovery, monitoring and configuration of connection

devices and end-point devices are made available on this interface

Out- band

Most end point devices has one or more interfaces are not directly connected tothe storage network, but are available on a second, separate channel.

In general, these are LAN connections and serial cables. This channel is not

intended for data transport, but is provided exclusively for management purposes.

This interface is therefore called out-band.

Standardized

Proprietary


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System Management


Standardized : The standardisation and developmet for in-band management is found at two levels.

In-band transport levels: The management interfaces for Fibre Channel, TCP/IP andInfiniBand are defined on the in-band transport levels.

In-band upper layer protocols (ULP) : Primarily SCSI variants such as Fibre Channel FCP

and iSCSI are used as an upper layer protocol. SCSI has its own mechanisms for requesting

device and status information: the so-called SCSI Enclosure Services (SES). In addition to the

management functions on transport levels a management system can also operate these

upper layer protocol operations in order to identify an end device and request status

information.

Proprietary:

APIs: Proprietary interfaces are differentiated as application programming interfaces (APIs),

which are used to call special management functions.

Telnet and Secure Shell (SSH) based interfaces and element managers. A great number of

devices have an API over which special management functions can be invoked. These are

usually out-band, but can also be in-band, implementations.

Element manager: An element manager is a device-specific management interface. It is

frequently found in the form of a graphical user interface (GUI) on a further device or in the

form of a web user interface (WUI) implemented over a web server integrated in the device

itself. Since the communication between element manager and device generally takes place

via a separate channel next to the data channel, element managers are classified amongst the

out-band management interfaces.


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System Management


In-band Management:In-band management runs over the same interface as the one that connects

devices to the storage network and over which normal data transfer takes place.

This interface is thus available to every end device node and every connection

node within the storage network. The management functions are implemented as

services that are provided by the protocol in question via the nodes.

Two types of services:

Operational services: Operational services serve to fulfil the actual tasks of

the storage network such as making the connection and data transfer.

Management specific services : Management-specific services supply the

functions for discovery, monitoring and the configuration of devices.

In order to be able to use in-band services, a so-called management agent isnormally needed that is installed in the form of software upon a server connected

to the storage network. This agent communicates with the local host bus adapter

over an API in order to call up appropriate in-band management functions from an

in-band management service.


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System Management


In-band Management:

In-band management runs

through the same interface

that connects devices to the

storage network and via

which the normal datatransfer takes place. A

management agent

accesses the in-band

management services via

the HBA API.


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System Management


In-band Management: Fibre chanel SANServices for management: Each service defines so called one or more servers. Servers are split

into individual components and implemented in distributed form by connecting individual

components through fibre channel SAN.

Directory services

Management service

Types of servers

Name server: The name server is defined by the directory service. It is an example of an

operational service. Its benefit for a management system is that it reads out connection

information and the Fibre Channel specific properties of a port (node name, port type).

Configuration Server: The configuration server belongs to the class of management-specific

services. It is provided by the management service. It allows a management system to detect

the topology of a Fibre Channel SAN.

Zone server: The zone server performs both an operational and an administrative task. It

permits the zones of a Fibre Channel SAN fabric to be configured (operational) and detected

(management-specific).


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System Management


In-band Management: Fibre chanel SANDiscovery

The configuration server is used to identify devices in the Fibre Channel SAN and to

recognise the topology. The so-called function Request Node Identification Data (RNID) is

also available to the management agent via its host bus adapter API, which it can use to

request identification information from a device in the Fibre Channel SAN. The function

Request Topology INformation (RTIN) allows information to be called up about connected

devices.

Suitable chaining of these two functions finally permits a management system to discover the

entire topology of the Fibre Channel SAN and to identify all devices and properties. If, for

example, a device is also reachable out-band via a LAN connection, then its IP address can be

requested in-band in the form of a so-called management address. This can then be used by

the software for subsequent out-band management.


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System Management


In-band Management: Fibre chanel SAN

Monitoring

Since in-band access always facilitates communication with each node in a Fibre Channel

SAN, it is simple to also request link and port state information. Performance data can also be

determined in this manner. For example, a management agent can send a request to a node in

the Fibre Channel SAN so that this transmits its counters for error, retry and traffic. With the aid

of this information, the performance and usage profile of the Fibre Channel SAN can be

derived. This type of monitoring requires no additional management entity on the nodes inquestion and also requires no out-band access to them. The FC-GS-4 standard also defined

extended functions that make it possible to call up state information and error statistics of other

nodes. Two commands that realise the collection of port statistics are: Read Port Status Block

(RPS) and Read Link Status Block (RLS).


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System Management



Messaging

In addition to the passive management functions described above, the Fibre Channel

protocol also possesses active mechanisms such as the sending of messages, so-called

events. Events are sent via the storage network in order to notify the other nodes of status

changes of an individual node or a link. Thus, for example, in the occurrence of the failure of a

link at a switch, a so-called Registered State Change Notification (RSCN) is sent as an event

to all nodes that have registered for this service. This event can be received by a registeredmanagement agent and then transmitted to the management system.


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System Management



Zoning Problem:

In addition to the passive management functions described above, the Fibre Channel

protocol also possesses active mechanisms such as the sending of messages, so-called

events. Events are sent via the storage network in order to notify the other nodes of status

changes of an individual node or a link. Thus, for example, in the occurrence of the failure of a

link at a switch, a so-called Registered State Change Notification (RSCN) is sent as an event

to all nodes that have registered for this service. This event can be received by a registeredmanagement agent and then transmitted to the management system.


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System Management



Services for management: Two services

Directory services

Management service


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Data storage management and retrieval

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