8/6/2019 Course Session 306012 Introduction to Storage Networks http://slidepdf.com/reader/full/course-session-306012-introduction-to-storage-networks 1/34 ntroduction to storage networks Flexible and redundant storage can solve many network problems, and storage area networks (SANs) rovide the solution. In this class, you'll learn the range of current storage issues and settings and dentify areas that provide tangible returns for an investment in storage networks. Along the way, you'll earn about SAN disks, host bus adapters, switches and management tools. Lessons Is a storage area network right for your organization? 1. In this first lesson, you'll learn the role of storage network solutions in adapting your organization's network from a patchwork quilt of single-purpose servers to an interwoven fabric of storage resources. Exploring virtual storage 2. In this lesson, you learn what virtual storage is and discover its benefits. You also learn how using an all-in-one solution can help you get started quickly and easily and review migration and upgrade paths for moving your data. Understanding SAN disk solutions 3. In this lesson, you'll delve into the technologies behind SANs. You'll learn about data protection with redundant drives and data backup, as well as performance implications in designing a SAN. Discovering SAN controllers, cables and connectors 4. SANs are made up of two main components: storage devices, in the form of disk and tape drives, and networking components, which include adapters, cables and switches. In this lesson, you learn about the networking components of a SAN. Exploring topologies and switches 5. This lesson focuses on ways to interconnect storage network components. You'll learn about topologies and the role of switches and the services they provide. You'll also delve into more detail on the switches that tie a SAN together. Managing and administering SAN software 6. SAN systems require management to keep them running smoothly. This lesson covers using management software, zones, policy-based tools and LUN masking to ensure your SAN is secure and functioning efficiently. s a storage area network right for your organization? n this first lesson, you'll learn the role of storage network solutions in adapting your organization's network from patchwork quilt of single-purpose servers to an interwoven fabric of storage resources. Welcome to Introduction to storage area networks Welcome to Introduction to storage networks. Storage of your organization's data is critical to its business perations. Every day, users access, modify and share data that enables the organization to function. However, data storage can quickly become unmanageable when storage capacity must increase to ccommodate the vast quantities of information created daily and stored for months or years. This class xplains how to investigate your organization's storage needs and evaluate storage technologies to etermine which best fits your requirements. This class is geared toward IT personnel who are responsible for network storage planning for small and medium-size businesses (SMBs). One solution to meeting data storage needs is using a storage area network (SAN)—a centrally onsolidated, virtual disk storage system that's separate from network traffic and shared by servers.
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8/6/2019 Course Session 306012 Introduction to Storage Networks
ntroduction to storage networksFlexible and redundant storage can solve many network problems, and storage area networks (SANs)
rovide the solution. In this class, you'll learn the range of current storage issues and settings and
dentify areas that provide tangible returns for an investment in storage networks. Along the way, you'llearn about SAN disks, host bus adapters, switches and management tools.
Lessons
Is a storage area network right for your organization?1.
In this first lesson, you'll learn the role of storage network solutions in adapting
your organization's network from a patchwork quilt of single-purpose servers to
an interwoven fabric of storage resources.
Exploring virtual storage2.
In this lesson, you learn what virtual storage is and discover its benefits. You
also learn how using an all-in-one solution can help you get started quickly and
easily and review migration and upgrade paths for moving your data.Understanding SAN disk solutions3.
In this lesson, you'll delve into the technologies behind SANs. You'll learn about
data protection with redundant drives and data backup, as well as performance
implications in designing a SAN.
Discovering SAN controllers, cables and connectors4.
SANs are made up of two main components: storage devices, in the form of
disk and tape drives, and networking components, which include adapters,
cables and switches. In this lesson, you learn about the networking components
of a SAN.
Exploring topologies and switches5.
This lesson focuses on ways to interconnect storage network components.
You'll learn about topologies and the role of switches and the services theyprovide. You'll also delve into more detail on the switches that tie a SAN
together.
Managing and administering SAN software6.
SAN systems require management to keep them running smoothly. This lesson
covers using management software, zones, policy-based tools and LUN
masking to ensure your SAN is secure and functioning efficiently.
s a storage area network right for your organization?n this first lesson, you'll learn the role of storage network solutions in adapting your organization's network from
patchwork quilt of single-purpose servers to an interwoven fabric of storage resources.
Welcome to Introduction to storage area networks
Welcome to Introduction to storage networks. Storage of your organization's data is critical to its business
perations. Every day, users access, modify and share data that enables the organization to function.
However, data storage can quickly become unmanageable when storage capacity must increase to
ccommodate the vast quantities of information created daily and stored for months or years. This class
xplains how to investigate your organization's storage needs and evaluate storage technologies to
etermine which best fits your requirements.
This class is geared toward IT personnel who are responsible for network storage planning for small
and medium-size businesses (SMBs).
One solution to meeting data storage needs is using a storage area network (SAN)—a centrally
onsolidated, virtual disk storage system that's separate from network traffic and shared by servers.
8/6/2019 Course Session 306012 Introduction to Storage Networks
Figure 1-1: A SAN fabric is made up of many interconnected fiber optic strands.
Enlarge image
In many computer networks, workstations and servers have a single connection to the network, but a
SAN fabric has multiple connections.
Redundant connectivity reduces downtime for users, which is important to ensuring high availability for
ata and network resources. A SAN's separate, centralized setup also reduces downtime and offers the
ollowing benefits:
Reduces the space required for a one-application, one-server setup
Eases the burden of management tasks, including backups and recovery
Reduces the incremental costs associated with adding storage
Increases the visibility into planning for storage growth as an organization
Improves security by separating storage processes from normal network traffic
An important concept of SANs is the "virtualization" of data storage. Because storage is centralized as a
irtual pool of resources, you can allocate storage to servers as needed quickly and easily. With recent
egulations mandating that some industries, such as health care, retain data for longer periods, manyrganizations are facing rapidly expanding storage requirements. Virtual disk storage makes handling this
storage explosion" easier.
To understand the benefits a SAN can have for your organization, comparing the strengths and
weaknesses of DAS and NAS systems with SAN technology is helpful. Table 1-1 compares the basic
eatures of each technology.
Storage
feature
DAS NAS SAN
Storage
capacity
Limited to ports on the local
server
Not limited Not limited
Speed of
accessing
storage
Fast Somewhat slow Very fast
Ease of
adding
storage
Might require shutting
down servers to add
storage
Easy Easy
Redundant
connectivity
No No Yes
Centralized
management
No No Yes
Ease of expansion Limited to host's physicalports Allows modest expansion Quick and easy
Because SAN technology offers different advantages from an NAS or DAS system, you might want toreate a hybrid system incorporating each of these technologies. For example, a developer's server that's
sed to test new changes to a production application may need to be a very low cost implementation with
ttle consideration for performance. This type of server may use very low cost DAS to support a small
esting database. Production servers supporting the same application will no doubt support more users
nd require the performance and scalability that a SAN provides. To help you make that decision, assess
he importance of the following factors as you compare the features in Table 1-1:
Performance
Availability
Scalability
Cost
As you can see, SANs offer a fast, flexible method for connecting consolidated storage to the servers in
our organization. By efficiently allocating storage resources as they're needed, your organization will
ave both time and money by reducing the overspending on unmanaged DAS or NAS storage resources.
As you delve into the technical details of SANs in upcoming lessons, these benefits will be even more
pparent.
Now that you've seen what SANs can offer your organization, continue reading to learn how to assess
our current environment to determine whether a SAN solution is right for you.
Taking inventory and assessing your storage needs
To understand how your organization can benefit from using SAN technology, you need to take inventory
f the storage you currently use and get a handle on your projected future needs. Getting an accurate
iew of your organization's overall storage picture can be daunting, especially if each department has its
wn standalone storage. If your organization has been adding storage over a long period for different
unctions—an email server one year and a database server the next year, for example—this task can be
ven more challenging.
Although taking an inventory of this type of "server sprawl" setup can be time consuming, the results can
elp you present a compelling case for using a SAN. For example, scattering storage all over the network
nevitably means duplication of IT management efforts. Upper management usually responds favorably to
he potential for a good return on an investment (ROI) in SANs if you can show a reduction in the
verhead of having several IT staff performing the same management tasks.
Although advantages such as redundant connectivity and more efficient backups are clear benefits of
SAN vs. DAS and NAS to those working directly with the network, upper management might not view
these advantages with the same weight as factors offering a clear-cut ROI, such as allowing the staff
to do more in less time and efficiently allocating storage using centralized management tools.
The assignment for this lesson explains in more detail how to create an inventory of your current storage
equirements. In general, you want to collect information such as the following:
Storage devices, including type (DAS or NAS, for example), capacity and location
Host machines
Connection devices, such as switches and bridges
Any distance considerations—for example, LANs in branch offices
Applications, including performance and availability requirements
8/6/2019 Course Session 306012 Introduction to Storage Networks
n addition, review your past growth in storage requirements to estimate how much your storage capacity
eeds might increase in the next year. The goal is to make sure your storage solution can handle future
xpansion without unnecessary downtime and management headaches as well as to keep the costs from
piraling out of control.
n upcoming lessons, you delve into the nuts and bolts of SAN technology and learn more about disk
rives, SAN switches and network cards, external cabling and software management tools.
Moving on
n this lesson, you reviewed traditional data storage options and learned that SANs combine flexibility with
igh-speed connectivity and consolidate your organization's storage in a centralized virtual storage pool.
n Lesson 2, you learn more about SAN features and options for building a high-performance SAN to
ncrease your data storage sensibly. Before you move on, complete the assignment and take the quiz for
his lesson. See you there!
Assignment #1
Your assignment for this lesson is to make an inventory of your organization's current data storage.This task might sound easy, but even small organizations often have data spread over many storage
evices, such as USB drives, server hard disks and NAS systems. Collect the following information,
triving for as much detail as possible. You might find it helpful to put your information in a
preadsheet for easy reference.
List all storage devices (with make and model) used in your organization. Include each device's
storage capacity (used space and free space), type of storage (DAS, NAS and so on), type of
connection it supports and location.
List the total number of host machines (workstations, servers and so on). For each host, include the
operating system (OS), type of connection it supports and applications running on it.
List all connection devices, such as switches and bridges, including their type and connection
speed.
List any distance considerations, such as LANs in branch offices that require storage.
List all applications your organization uses with their current storage requirements. Include
performance and availability requirements for users. You might also want to specify traffic patterns
for applications, such as peak periods of use.
Calculate the total amount of storage your organization uses.
After assessing the current state of your storage situation, projecting future storage needs and
nderstanding how a SAN can improve your data management are easier.
Quiz #1Question 1:
How does a SAN differ from an NAS system?
A) SANs use only fiber optics.
B) SAN and NAS are different acronyms for the same thing.
C) Network activity on a SAN is separate from other server and user traffic.
D) Network activity on an NAS system is separate from other server and user traffic.
Question 2:
Which of the following is a compelling advantage you can use to convince upper management that a SAN's
onsolidated storage is the best option?
A) Reducing duplication of IT management's time and effortsB) Using current network bandwidth for storage processing
C) Reducing space requirements
D) Increasing data backup speed
Question 3:
8/6/2019 Course Session 306012 Introduction to Storage Networks
True or False: An NAS system is faster than a DAS system because it uses the underlying network's data
ransfer rate.
) True
B) False
Question 4:
What advantages can a SAN offer over DAS and NAS solutions? (Check all that apply.)
A) Lowest cost
B) Centralized management
C) Reduced downtime
D) Fast data transfer speeds
Question 5:
Which of the following storage solutions is the most difficult to expand?
A) Storage area networks
B) Network attached storage
C) Server-based storage
D) Direct attached storage
Exploring virtual storagen this lesson, you learn what virtual storage is and discover its benefits. You also learn how using an all-in-one
olution can help you get started quickly and easily and review migration and upgrade paths for moving your
ata.
Understanding virtual storage
Welcome back! In Lesson 1, you reviewed the storage technologies organizations often use, compared
hem with SAN technology to see the flexibility and efficiency SAN offers. We covered how, when
ompared with DAS and NAS technologies, SAN provided:
Unlimited storage provisioning
Superior management of consolidated storage
Higher performance
You also learned the importance of doing a thorough inventory and assessment of your current and future
torage needs. As you work through this lesson, keep your Lesson 1 assignment handy. You can refer to
his inventory of your current storage as you learn about SAN storage capabilities in this lesson.
Storage consolidation
Storage consolidation is a major benefit of using SANs. With consolidation, you can manage separaterives and drive array storage units as part of a larger pool. As you learned in Lesson 1, storage
echnologies are based on the building block of a single physical drive. Adding drives requires some sort of
onnectivity and power to make it possible to use the storage. By consolidating these connections within a
torage unit, drive connections are made using an internal wiring harness that both eliminates clutter, but
more importantly, allows each drive to be replaced independently should it fail.
Lesson 3 explains the details of how physical drives are connected in a SAN.
Each physical drive added to a server or storage unit, as shown in Figure 2-1, requires separate power
nd connectivity cabling to make it work. As storage units are filled with drives, more storage units must bedded. Each storage unit also requires some kind of connectivity so that the drives in the unit can transfer
ata to and from systems using that storage.
8/6/2019 Course Session 306012 Introduction to Storage Networks
Figure 2-1: Drives are aggregated into storage units.
Building blocks of storage
This growing collection of drives housed in multiple cabinets (storage units) isn't useful without a way to
manage all the raw storage, however. Management is where the power of SAN technology starts to shine.
With SAN technology, the storage space on each drive is divided logically into storage blocks, as shown in
Figure 2-2, that can be assigned as a larger group spanning multiple physical drives.
Figure 2-2: Logical storage blocks on a physical drive.
Enlarge image
These storage blocks are managed as a single virtual storage device called a storage pool. Managingtorage as a pool makes it possible to allocate a portion of the storage to individual servers that are
onnected to the consolidated storage on the SAN. For example, when a server requires storage space,
ou can assign it as a group of storage blocks that might span many different physical drives in that
torage pool. Virtual storage hides the underlying physical infrastructure's complexity so that you can
llocate storage to meet servers' needs more easily.
By abstracting the way a server sees storage from the way drives actually read and write it, the
possibilities for adding, moving and copying storage become interesting, as you see later in this
lesson.
Volume allocation
As shown in Figure 2-3, physical drives have a number of storage blocks allocated to provide servers with
olumes used to store data. These volumes are allocated storage blocks based on a server's needs, as
Look for vendors that offer both all-in-one and enterprise-level storage solutions. All-in-one products
often incorporate the expertise used to develop the more expensive enterprise-level products in a
vendor's line but at a lower cost and with more simplified management tools.
By using an all-in-one solution that combines hardware and software, you can do the following more
asily:
Consolidate your storage.
Reduce your data center space requirements.
Reduce expenditures on extra storage.
Manage the storage your organization already owns more efficiently.
n addition, most all-in-one solutions have quick-start guides and data migration utilities so that you can
tart using new storage solutions in your current environment quickly and easily. After all, you want to
migrate your data to a new, more manageable storage platform as soon as possible.
Don't dismiss all-in-one SAN products as lightweight alternatives to the "real thing." Many all-in-one
roducts have more features than your current solution.
Many all-in-one SAN products allow you to integrate your new storage into the current environment by
everaging the infrastructure that exists within your current network. For example, advanced SAN
nstallations require multiple switches, fiber-optic cabling and training to maintain the new infrastructure.All-in-one solutions allow you to connect to your existing LAN switching gear with standard copper wiring
nd offer integrated electronics to manage new drives in the storage unit. We'll cover some of these
onnection details in Lesson 3 as we go over the connectivity options that are available when setting up a
SAN system.
All-in-one solutions are an easy way to get started with SANs. What do you do, however, when you
utgrow your all-in-one solution's capacity?
Understanding migration and upgrade paths
Storage growth is inevitable in organizations. As you've seen in this lesson, virtual storage allows
llocating storage blocks to servers as needed and allocating unused storage to new servers you've
dded. However, at some point, you'll run out of storage. What options do you have?
At some point, your organization will need to add storage, and SAN technology can make that process
easier.
Adding storage
One option is simply adding more physical drives to your current setup. With a SAN's block-level
llocations, this option is easier than with other storage technologies. New drives become part of the
irtual storage device, and their storage blocks can be allocated as needed. When new storage is needed
y expanding server volumes, it can come from many different drives in the SAN infrastructure. To make
his process even easier, SAN management software controls how server volumes use storage blocks
ehind the scenes. SAN technology ensures that increasing storage by adding physical drives is done as
fficiently as possible so that you don't purchase more drives than you actually need.
Migrating storage
Another option is purchasing a new storage solution and moving your current data to it. As with any
echnology, newer, faster or less expensive storage solutions that your organization wants to take
dvantage of will become available, or perhaps your organization has outgrown the capacity of the all-in-
ne solution you started with. When you purchase new SAN hardware, you need a way to move data on
our current SAN infrastructure to the new hardware.
8/6/2019 Course Session 306012 Introduction to Storage Networks
ncreasing the density of data stored on a platter is essential for getting large-capacity drives.
Although higher densities allow for larger capacities, the technology might not always translate to faster
performance.
Platter rotational speed
nside each drive, a motor spins the platter, allowing the heads to float over the platter's surface and read
he data on it. As platter speed increases, so does the drive's power consumption, heat output and noise.
This added speed reduces the time needed to make an entire rotation, however. If data is read on one
ass before the head moves to another area to read the next set of data, it happens more quickly with a
aster rotational speed. The following table shows different uses for platter speeds in rotations per minute
rpm).
Platter rotational speed Typical use
7,200 rpm File storage, inexpensive server storage
10,000 rpm Mid-range database storage, streaming video storage
15,000 rpm High-use database storage, high-definition video editing storage
Table 3-1: Typical uses of platter rotational speeds.
You might think that using the fastest drive available is the best option, but keep in mind that the faster the
latter rotational speed, the more expensive the drive is. For a database that doesn't get much use, for
xample, buying a 15,000 rpm drive isn't cost effective. You'll have more speed than you need, and power
onsumption, heat output and noise will be higher than necessary.
Connectivity bandwidth
esson 1 covered connectivity types for drives (SCSI, ATA, serial ATA and USB). These connectivity
ptions enable data to be streamed from the drive to applications that need it. Some options are faster thanthers, which allow drive heads to pump data from the platter continuously. As you might imagine, the
andwidth of these connections can affect data flow if the heads can read more data than the connection
an transfer. If the connectivity cannot stream the data as fast as it's read from the drive, the drive will
uffer some of the data temporarily in a small on-board memory chip. However, once the RAM buffer
apacity is reached, the drive will wait to read more data. This increases the potential delay as the platter
pins and the data that would have been read moves farther out of position until the full rotation finally
rings it back around to the head's position.
Considering your RAID configuration
You've been concentrating on the performance of data streaming from drives, but you should also consider
ow to protect data stored on drives. Component failures are inevitable, so planning for these failures is
ssential. The primary mechanism for managing data replication in a SAN is a redundant array of
nexpensive drives (RAID) system. The following table describes the available RAID levels.
RAID
evel
Description
RAID
0
Creates data "stripes" across multiple drives, which makes it possible to read data more quickly than
on a single drive but doesn't protect data if any drive fails.
RAID
1
Creates a mirrored drive set, in which data is written to two duplicate drives simultaneously. If one
drive in the mirrored set fails, the other drive can still operate and store all the data.
RAID
3
Creates a striped data set similar to RAID 0 but includes an extra drive containing additional
information called parity data. With this feature, if one drive in the set fails, lost data can be re-
created so that the drive set can continue operating.
RAID
5
Similar to RAID 3, but parity data is striped across the entire group of drives instead of being stored
on one dedicated drive. Therefore, every drive can manage a portion of the drive set's parity data.
RAID
10
In this combination of RAID 1 and RAID 0, data is striped across a set of drives and then mirrored to
another set of drives. This type of mirroring removes the extra step of calculating parity data every
8/6/2019 Course Session 306012 Introduction to Storage Networks
A SAN system can usually support every RAID level, so you can configure a RAID level based on the
torage allocated to the server. Some factors that help you determine the right RAID level include the
ollowing:
Tolerance for delays in writing to the drive
Performance effects during the RAID rebuilding phase
Tolerance for the RAID rebuilding process when a drive fails
Tolerance for writing delays
When data is written to a RAID system, the RAID software (whether on a chip or in firmware on the
ontroller) must calculate parity data before data is written to drives in the set. This calculation is usually
apid but still requires time. RAID 5 works for most applications; however, if the SAN volume using RAID
as a lot of activity, application performance might be affected. In this case, consider using RAID 1
mirroring) to eliminate the overhead of parity calculations. Just remember that you'll spend twice as much
n storage because every drive has a mirrored duplicate drive.
Performance effects during RAID rebuilding
When a drive in the RAID set fails, every operation must undergo a RAID parity calculation to make up for
he drive that failed. This process reduces the RAID system's overall read performance. Additionally, when
new drive is installed to replace the old drive, every byte of data on the volume must be recalculated and
opied to the new drive. During this operation, the RAID system's performance degrades.
Tolerance for RAID rebuilding when a drive fails
Most RAID hardware monitors idle periods to reduce the impact of the rebuilding process, at the cost of
aking longer to rebuild data. During rebuilding, therefore, data is at risk of a secondary failure. RAID 1mirroring) has a similar rebuilding process, but read performance isn't affected as much because there's
o need to recalculate parity data. However, managing a mirrored set requires twice as much storage.
Remember that RAID levels above 0 (simple striping) always require more drive space to protect your
data. This drive space costs more but adds redundancy to your SAN for data protection.
These factors, weighed against the costs and survivability requirements you have for certain types of data,
elp you determine which RAID level to use. You have other options for storing backups of your data,
owever, that don't involve using drives. The next section discusses non-disk storage options.
Backing up data with non-disk storage
Storing data on a SAN has an often overlooked advantage. When you store data on traditional DAS
ystems, the server needs to spend cycles reading the data to back it up to a local or networked drive. So
uring backup operations, the server's performance is reduced, and the load on the local area network
LAN) increases. The time a backup operation takes is called the backup window. The more data a server
as, the longer the backup window is. As you continue adding storage, the backup window might be longer
han the "off hours" you've allotted for backups (usually nights or weekends). When the backup window
pills over into normal work hours, the performance of an organization's day-to-day operations is affected.
Organizations use three basic types of backups:
Full backup: All data on the volume is copied.
Differential backup: All data that has changed since the last full backup is copied.
Incremental backup: All data that has changed since the last incremental backup is copied.
8/6/2019 Course Session 306012 Introduction to Storage Networks
The following table summarizes each backup type's advantages and disadvantages.
Backup
type
Advantage Disadvantage
Full
backup
All data is copied, so you have a complete set of data if recovery is
required.
Takes the
longest to
complete and
requires the
most storage
because all data
is being copied.
Differential
backup
This type is a good compromise between full and incremental backups. It
requires less storage and takes less time than a full backup, and fewer data
sets are needed to restore the volume to the last full backup than with
incremental backups.
As the time from
the last full
backup
increases and
more files are
modified,
backups take
longer and
require more
storage.
ncremental
backup
This type is the fastest and requires the least amount of space because
only data that has changed since the last incremental backup is copied.
If recovery is
needed, this
method requires
restoring the
most data sets.
The full backup
plus every
incremental
backup since
the full backup
are needed to
restore the
current volume.
Table 3-3: Backup types.
Because a SAN maps storage into virtual volumes and assigns them to separate servers, it maintains
ontrol over all storage components. Most SANs include a tape system for reading data directly from the
SAN instead of through each server. This backup advantage reduces the amount involvement that the
ervers themselves as well as eliminating the LAN traffic.
For example, if your organization has five servers, with 100 GB of data allocated to each, the SAN-
ttached tape system can access all 500 GB of data through the SAN, instead of pulling data from each
erver. During a tape backup, the SAN can be instructed to create a snapshot, in which all data at a point
n time is "frozen." During a snapshot backup, the SAN maintains any changes that would normally be
pplied to the file in a way that the data is actually written to after the backup of the file is completed.Unless a file is extremely large, the backup will usually complete without requiring a large number of
elayed writes. Figure 3-1 illustrates this process.
8/6/2019 Course Session 306012 Introduction to Storage Networks
SAN, the network is a high-speed channel designed to move data between storage devices to servers and
etween tape systems and storage devices. Figure 4-1 shows how these components are connected.
Figure 4-1: Networking components of a SAN.
Enlarge image
Host bus adapters
A host bus adapter (HBA) is a card or device added to a server to manage the transfer of information and
nable the server to communicate in a certain way. You're probably familiar with network interface cards
hat are used with desktops to communicate with a LAN via Ethernet. Similarly, wireless network interfaceards are used to connect laptops via Wi-Fi to a LAN. These HBAs provide a communication channel over
which data flows between a host and network devices.
SAN HBAs serve the same purpose: connecting servers to storage over a dedicated high-speed network
hat's separate from the LAN. However, HBAs are not simply network cards for your SAN. These cards
ffer high-speed processors that remove a large burden from the host's operating system and main CPU.
Creating a "virtual drive" for your server's operating system, the HBA and its driver software mask the
omplex communications that goes on behind the scenes between the HBA and the rest of the SAN.
Additionally, HBAs offer the ability to manage communications to the SAN in a way that increases the
verall throughput of your server's applications. The HBA creates multiple communications links to thetorage devices on the SAN and manages them separately. For example, if one application on your server
s transferring a large bulk of data to a SAN storage device that's under a heavy load, the HBA may have
o wait to send data to that storage device. However, another application on the server may be accessing
database that's not experiencing heavy loads, therefore the HBA can continue streaming the data
etween the server and the database without being affected by the other communications that are waiting.
Cabling
Data flows from a server's HBA over some type of cabling. This cabling can be copper, but often fiber-optic
abling is used for connectivity over longer distances and resistance to outside electromagnetic
nterference (EMI ). Copper cabling usually involves lower costs, but the main goal of a SAN is less aboutost and more about protecting data integrity. However, as you'll see shortly, the types of cabling used in
SANs can vary, depending on the underlying network infrastructure. For example, Fibre Channel
onnectivity uses fiber-optic cabling, and iSCSI might use copper cabling through existing switches.
Switches
Switches, the backbone of a SAN network, provide connectivity between servers and storage devices.
These devices are available in different networking technologies, and your decision on which one to use is
sually based on your current infrastructure and your selection of other SAN components. Next up, you
earn how to evaluate SAN networking technologies, considering factors such as available support, costs
nd flexibility.
Evaluating SAN networking technologies
Some LANs use networking technologies such as token ring, Attached Resource Computer network
Competing with LAN traffic for available bandwidth
Requiring extra steps for installation
Redesigning your existing LAN to accommodate SAN components
When you use your current LAN infrastructure for a SAN's high-use traffic, competition for bandwidth could
e a problem. Printers, workstations and other servers might be affected by traffic bottlenecks if the
etwork isn't designed to handle the additional SAN traffic. When installing iSCSI, therefore, you might
eed to segment your network or add new switch ports to manage the SAN's extra storage devices. These
hanges could involve some network redesign, which may increase your time and effort. However, if your
etwork is already built for high-use traffic and is designed to handle new applications, such as a SAN,
SCSI can be an easy way to deploy a SAN with your current hardware and cabling.
nfiniBand
One of the newest SAN networking technologies is InfiniBand, which offers support from major
manufacturers but is still fairly new. Unlike the Peripheral Component Interconnect (PCI) bus used with
ther networking technologies, InfiniBand can carry multiple channels of data at the same time to improve
hroughput. With a low-overhead protocol and high-speed throughput, InfiniBand could overtake Fibre
Channel in the future.
The Infiniband specification provides for both copper and fiber optic cabling standards. With copper
abling, you have a limited distance of about 45 feet (or 15 meters) while fiber optic cabling provides for onnectivity up to 900 feet (or 300 meters). An organization investing in Infiniband technology for a SAN
would want to invest in the fiber optics to ensure that there are not expansion limitations once you've
mplemented your SAN.
Even with these benefits, you need to consider a few drawbacks. Because InfiniBand is still fairly new, its
upport isn't as broad as Fibre Channel support. Also, as with any emerging technology, some early-
dopter issues need to be worked out before InfiniBand can be considered ready for widespread use.
Currently, even with large names backing the technology, there are few second-tier providers that are
ffering products based on Infiniband. This may limit your options when your organization purchases
quipment to build out your SAN. InfiniBand could still be an excellent selection for your organization,
owever. Major companies, such as IBM, Microsoft, Dell, HP, Intel and Sun Microsystems use it, and it
as been used in super-computing applications around the world. However, compared to the FibreChannel support base, InfiniBand still can't be considered the standard SAN implementation.
After deciding which networking technology you want to use for a SAN, you need to select an HBA. Next
p, you learn some factors to consider when picking one.
Selecting an HBA
After selecting a SAN networking technology, the HBAs you decide to use have an effect on throughput
performance), reliability and scalability. In this section, you review some key decisions to make whenou're evaluating HBAs to use in your SAN.
Vendor recommendations
When you're building a SAN, consider HBA recommendations from the vendor of your SAN switching
ardware and storage devices. Vendors typically recommend their own HBAs for use in a SAN, but try to
et unbiased opinions from them, if possible. If not, most vendors have a list of supported HBAs on which
hey've tested their equipment, which you can find on their websites or in their support documentation.
Port speeds
While port speeds are a factor of both the HBA and the switch, you'll need to determine what speed you'll
e implementing. Often, this is a factor of pricing for the HBA. Faster cards are more expensive, and your
udget for these HBA cards could quickly be exhausted by purchasing the fastest cards your switch can
upport.
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As a general rule, increase the budget for connectivity to storage devices where many servers will be
onnected while maintaining the more affordable connectivity for typical servers within a server farm.
Cabling type
As mentioned, you want to select an HBA that supports the cabling and other infrastructure components
ou're using. Most vendors offer the type of card you need for your platform. If you're using more
dvanced topologies, such as server blades, or a less common server platform, however, you might need
o use HBAs from different vendors to fit your network's needs.
HBA management tools
Most HBAs include configuration and management software. If you plan to use a single vendor for all SAN
omponents, managing HBAs over the SAN with the vendor's software is usually adequate. However, if
ou're using an enhanced management tool, make sure it supports the HBAs you've decided to use in
our environment. The HBAs you select may offer diagnostic options that will help keep your servers
eliably connected to the SAN. These HBAs can contact the management tools to offer a warning in case
he HBA is experiencing high error rates or memory issues.
Enhanced features
Some HBAs have enhanced features that offload tasks the main CPU might have to perform to
ommunicate on the SAN as described earlier in this lesson. These offload features, such as drive
irtualization and data transmission optimizations using a high-speed CPU on the HBA can dramatically
educe the load on a server's processors and improve its overall performance on the SAN.
Moving on
n this lesson, you learned about the major networking components of a SAN: HBAs, cabling and switches.
You also learned different options for SAN networking technology and factors to consider when selecting
n HBA. No matter what your choice for these components, make sure you consider factors such as
erformance, reliability and scalability so that your SAN can serve your organization's needs in the future.
Before you move on, do the assignment and take the quiz for this lesson.
Assignment #4
Review Lesson 4's list of factors to consider when selecting a networking technology for your
SAN, and then do the following:
Review Lesson 1's inventory to make sure you understand your network's needs.1.
Research the main networking technologies discussed in this lesson: Fibre Channel,2.iSCSI and InfiniBand. As you're researching, keep in mind the important factors to
consider and your current network infrastructure and requirements.
Select a SAN networking technology that best fits your organization's needs, and then3.
write a memo to management explaining your selection.
Quiz #4Question 1:
Which of the following is a SAN networking component? (Check all that apply.)
A) SwitchesB) Host bus adapters
C) Workstations
D) Cabling
Question 2:
True or False: Fiber-optic cabling should always be used in a SAN for protection against EMI.
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n addition to selecting a physical layout for connecting SAN device, you need to consider other factors in
our design. As you learn in the next section, one important consideration is incorporating redundancy into
our SAN to make sure you don't lose critical data after a network failure.
Continuity management options
Organizations sometimes overlook the need to consider operational continuity, which is the capability to
esume operations after a disaster. One way to ensure operational continuity is to build redundancy (alsoalled resiliency) into your SAN. Although adding redundancy increases costs, being able to maintain your
rganization's operations after a network failure is essential. To help you determine how much redundancy
ou need, ask management the following questions:
What's the organization's cost per hour during normal operations?
How does storage downtime affect the organization's operations?
How long can the organization tolerate unplanned downtime?
How much is the organization willing to spend to avoid unplanned downtime?
With this information, you can better estimate the financial impact of unplanned downtime and budget for a
edundancy solution. The following table compares costs and redundancy features of the major topologies
o help you make a decision.
Factor Ring topology Cascade topology Mesh topology Core/edge topology
Tolerance to failures Poor Poor Good Good
Performance Good Good Better Best
Scalability Some Some Poor Good
Cost Low Low High Medium
Table 5-1: Comparing topologies.
Redundancy within a topology permits individual failures to reduce the likelihood that connectivity to one or
more components are lost. If your organization has a low-tolerance for unplanned downtime due to its
xpense or criticality, spending more on a topology that offers good redundancy would offer a way to
educe the amount of unplanned outages. Obviously, the more redundant the connectivity is, the more
omponents that need to be purchased, installed and maintained over time.
After selecting a topology, you have other options for adding disaster recovery features. For example, if
ou use a core/ed e to olo , ou could desi n a multi-buildin SAN that can isolate switch failures to a
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pecific building or floor, as shown in Figure 5-6. Being able to isolate switch failures improves
erformance and redundancy because a single failure doesn't affect the entire network. Also, if you plan
horoughly, you could expand your SAN to favor local hosts based on their proximity. By adding storage
evices that are connected to local edge switches rather than connected to a switch on the other side of a
ore switch, you could reduce the amount of traffic flowing over the core switches, which allow more
hroughput for connections that have to traverse the core switches.
Figure 5-6: A multi-building SAN that incorporates core and edge switches.
Networking technologies haven't been mentioned because they usually have no effect on the SAN
topology you select. If you're creating an iSCSI SAN on top of your existing LAN, however, you might
need to consider whether your current LAN topology is capable of handling the extra SAN traffic.
Now that you understand how to select a topology, keep reading to learn what features to look for in SAN
witches to create your network topology.
Exploring switchesBecause SANs in a core/edge topology with Fibre Channel networking technology are the most common,
his section uses this setup to explain switch features you should consider for your SAN. SANs that are
uilt on a LAN using iSCSI would have similar topology considerations. In addition to the SAN traffic, the
AN switch design would also need to incorporate heavy usage internet and intranet traffic as well as
rinters and workstations. The same core/edge switch design would apply to an iSCSI SAN.
Basic switch features
SAN switches have several basic features that provide connectivity for edge devices, such as servers and
torage, as well as core switches. Each connection, or link, to a switch is made over a copper or fiber-opticable. One end connects to the network device, and the other connects to the switch port. You can set the
onnectivity speed on a switch port manually or configure it to negotiate the highest possible speed
utomatically.
n addition, other integrated components are used to report the status of a port and manage ports remotely
y using desktop or web-based management software. Typically, high-end switches have more
management and reporting features, but many entry-level switches incorporate these helpful features, too.
Web-based management software is a convenient alternative to desktop software but might not offer
as many features such as auto-discovery or real-time statistics.
Environmental factors have become a concern lately, so reducing power consumption and cooling
equirements is an important consideration. Most vendors now offer energy-efficient switches with reduced
ower consumption and cooling. In addition, look for power supply redundancy options to increase your
etwork's capability to withstand electrical fluctuations or outages. Even entry-level switches now offer
edundant power supplies that can be plugged into two different circuits in the data center.
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You can set up zones for switches that enable you to segment traffic for improving security and conserving
andwidth. If you create a zone for financial data, for example, only servers added to the financial zone
ave access to storage in that zone. With this setup, you can help prevent unauthorized access to financial
ata, which improves security.
n addition to creating zones to secure data, adding zones can reduce the likelihood that any one storage
evice gets overloaded. By creating multiple zones and assigning devices and servers to each zone, youan break up the traffic going to each of the devices so that requests are services more quickly and the
raffic within that zone is managed. If your organization created only one zone for all devices, it may be
ossible that the servers within the SAN could saturate the bandwidth to the storage devices.
Devices can be a part of more than one zone, too. For example, if you want all devices in your SAN to
hare the backup system, you could configure all devices to be part of the backup zone to give them
ccess to the tape backup unit. Zoning is a powerful tool for managing servers and data and is discussed
n more detail in Lesson 6.
SL trunking
nterswitch links (ISLs) are another option for connecting SAN switches. Switch links are combined to
reate a "trunk" or bundle of links that act as a single connection. This option increases bandwidth, so it
an handle more traffic. Also, it improves redundancy because if one link fails, other links in the trunk can
ontinue transmitting data. Figure 5-7 shows an ISL trunk in a topology diagram.
Figure 5-7: ISL trunking combines several switch links.
Enlarge image
f you're building a SAN that uses a different technology (such as 10 Gigabit Ethernet with iSCSI), make
ure you look for the same types of features discussed in this section. Many major vendors support these
eatures in iSCSI products to give you the same flexibility and capability of Fibre Channel SANs. Your
urrent LAN switches may already be capable of some of the features listed in this section which would
llow your organization to more easily implement an iSCSI solution.
Moving on
n this lesson, you learned some topology options for connecting SAN components. In addition, you
earned the importance of incorporating redundancy into your SAN topology and reviewed some features to
onsider when purchasing a switch. Lesson 6 puts together what you've learned in previous lessons and
eviews management options for your SAN. Before you move on, do the assignment, take the quiz for this
esson.
Assignment #5
For this assignment, do the following:
Review your organization's needs by looking over your assignments for previous1.
n Lesson 5, you explored SAN topologies and learned more about switches, which provide connectivity
or your SAN. To take advantage of all the power a SAN offers, in this lesson you learn how to select the
est management software for your solution and explore other options for managing your SAN.
Most SAN vendors have different packages of management software with features for administering and
eporting on SAN resources. These packages can be divided into three major categories:
Web-based software
Low-functionality workstation software
Premium-functionality workstation software
The following sections explore features of each category.
Web-based software
Web-based software usually has fewer features than workstation-based software. It can perform simple
asks and basic reporting but typically isn't used for an enterprise-level SAN system. Web-based software
oes offer the following benefits, however:
No software to install
Can be used from any workstation or even a remote location
Performs simple tasks easilyTypically free or included with equipment purchase
For a small or highly mobile organization, web-based software can be the perfect management solution.
Low-functionality workstation software
ow-functionality workstation software generally offers more resource-allocation functions than web-based
oftware. In addition, some low-functionality software can generate a topology map of your SAN and
eports for every device. The software must be installed from a CD/DVD and is usually run from an
dministrative workstation. Some vendors will include this type of software for a modest fee. Other
endors may even freely distribute a limited version of their premium-functionality software. Even if there is cost to this software, the added benefits are often worth the small cost. Most low-functionality software
lso includes the following features:
Produces a complete picture of your SAN resources for better visualization
Manages multiple switches
Automates tasks for efficient use of staff time
Uses industry-standard interfaces to manage multi-vendor platforms
Premium-functionality workstation software
Premium-functionality workstation software adds more enterprise-level features for capacity, performance
nd reporting. This software is typically more expensive than the low-functionality software discussedreviously. But the added costs for the premium-functionality can often provide a great deal of added
enefit in terms of efficiency. Software in this category enables you to do the following:
Plan for allocating storage capacity
Support storage infrastructure lifecycle management
Monitor performance of your SAN components
Get notifications for events such as low disk space or high resource use
Keep in mind that vendors release updated software versions constantly to stay competitive, so you might
e able to find some high-end features in a less expensive low-functionality package. Make sure you do
our homework on which features are important to your organization when evaluating management
oftware for your SAN. If you decide to purchase a premium-functionality package, make sure your
rganization really needs the features that it's paying for.
Now that you know what to look for in management software, keep reading to find out other management
ptions you have for your SAN.
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Managing resource accessibility is critical to maintaining SAN security. You can manage resource access
y designating device zones and LUN masking.
Designating device zones
As you learned in Lesson 5, you can divide your SAN devices into zones to make sure data is accessible
nly to resources allocated to a zone. A small SAN might have only one zone, but larger SANs could have
many zones. Zones are useful for simplifying management and increasing security.
You can compare using SAN zones to setting up groups to manage user rights. When you're assigning
ermissions to users for network resources, often you set up user groups to make this task easier. That
way, you don't have to assign permissions separately to each user. You assign permissions to a group
ou create, and then add users to the group as members.
The same is true of SAN zones. You can assign devices to zones as an easier method of managing rights
o storage resources. As with users who can be members of more than one group, devices can be placed
n more than one zone so that they can access several different storage resources. Tape backup systems,
or example, are typically given rights to all, or many, zones to make the backup process more efficient.
Figure 6-1 shows a switch assigned to both Zones A and B.
Figure 6-1: A device can be assigned to more than one zone.
You can create the following types of zones, explained in more detail in the following sections:
Hard zoning
Soft zoning
World Wide Name zoning
Hard zoning
Hard zoning, the strictest type of zoning, is configured in the device hardware and actually preventsevices from communicating and accessing resources outside their zones. Because it's implemented in
ardware, it's fast and secure. Consider hard zoning for highly confidential information, such as financial
ata or personnel records. one drawback of hard zoning is its lack of flexibility. After you've configured
oning for device hardware, changing zones can be more time consuming than with other zoning types.
Soft zoning
Soft zoning, as the name implies, is configured in device software as a filter for accessing resources. With
his type of zoning, when a device "sees" the SAN, it can see only the resources it has allowed to access
n its zone. Therefore, modifying your setup to add or overlap zones is easier than with hard zoning. Soft
oning is less secure because servers or devices in other zones might be able to guess device addressesdiscussed in the next section) and access resources outside their zones. However, most SANs aren't
pen to network devices outside the SAN, so this disadvantage isn't major for most organizations.
Worldwide naming zoning
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more resources with fewer people. The reporting features in this software are also useful for auditing your
SAN to ensure consistency and monitoring performance.
Now that you understand the options for managing a SAN, you're ready to build a SAN for your
rganization's storage. The next section reviews what you need to know to be successful.
Starting smart with your SAN
This section wraps up the class by reviewing guidelines for setting up and using a SAN solution. Withhese guidelines, you can start smart and create a SAN that serves your organization for years to come:
Assess your overall storage needs for the organization, not just by department.
Plan for storage growth to make sure you're purchasing cost-effective storage devices.
Review your options for networking technologies, and then pick one that provides the performance and
support you need.
Determine how you're going to migrate data to your new SAN, and then plan for how your server
resources will be affected during the transition.
Select a SAN solution that's the right size for your organization but is capable of growing to meet your
storage expansion needs.
If your organization doesn't need a high-end solution, remember that an all-in-one solution might be a
good fit.
Select a RAID level that protects your data yet offers the performance your applications need.
Use a backup solution that can read data directly from the SAN.
Select a SAN topology that offers the growth, performance and redundancy options your organization
needs.
Use SAN management software to streamline access to common functions and make configuring
security and storage capacity easier.
Document your network by using the management tools you've selected.
Review your growth and capacity planning objectives often to make sure you have storage ready when
your organization needs it.
Moving on
n this lesson, you've learned how SAN management software can ease the administrative burdens
ssociated with a SAN and reduce the personnel needed to manage your storage infrastructure. As
lways, take the quiz and do the assignment before moving on.
Assignment #6
Now it's time to put together everything you've learned in this class. Review the guidelines at the end of
esson 6 to help you determine the best SAN solution for your organization. Then starting with the
opology diagram you've created for Lesson 5's assignment, expand this diagram to illustrate your entire
SAN system. Label all hardware components, such as cabling, switches, backup devices, HBAs and
torage units, and then include the model and make for each device. Finally, put together a proposal for
management that specifies the networking technology, redundancy features and SAN management
ptions you're using and then include a cost estimate for your overall SAN solution.
Quiz #6Question 1:
Reconfiguring zones is easy with which type of zoning? (Check all that apply.)
A) Hard zoning
B) WWN zoning
C) LUN zoning
D) Soft zoning
Question 2:
True or False: Low-functionality workstation software is the best solution for a small or highly mobile
rganization.
) True
8/6/2019 Course Session 306012 Introduction to Storage Networks