Chung Phan

CSMN 601Spring 2001

Storage Area Network (SAN): The Technology Behind SAN

Agenda

Cover Background An Overview of SAN’s Topology

and Fiber Channel (FC) Technology

Planning and Managing SAN Management Perspective Conclusion

What is SAN? “A SAN functions as separate high-speed network,

similar to a LAN, that establishes a direct connection between storage resources, typically in a large redundant arrays of independent disks or RAID systems or robotic libraries, and servers or workstations.”

A SAN is built on a separate network topology and for the most part does not rely on LAN protocols

Background

Background (Cont.)

In legacy servers, storage is connected directly to server or via the same LAN or WAN to communicate and exchange data

But the capacity of disks attached to such server has grown exponentially in many cases multiple tera bytes. It is out of control...

Currently there 3 different types of configurations: SAS, NAS, SAN

Traditional model, storage attach server or (SAS) built on the Small Computer Systems Interface (SCSI) parallel bus architecture

Problem with SAS is associated with -Lack of speed-Propagation delay in the transfer data lines

Additional SAS...

Background (Cont.)

Server Attach Storage (SAS): usage and issue

Background (Cont.)

Network Attach Storage (NAS): usage and issue

Background (Cont.)

Storage Area Network (SAN): usage and issue

Background (Cont.)

• Example: notice that SAN has separate network clouds

SAN Topology and Fiber Channel (FC) Technology

SAN technology has been existing in the form of proposals and standards drafts for quite sometime, in 1995 the Fiber Channel architecture became ANSI standard and subsequently in 1996 the Fiber Channel products started to flood the market in huge volume

SAN Topology and Fiber Channel (FC) Technology (Cont.)

• The ANSI T11X3 approved 1995 with max 1.06Gbps• FC-3 for future use possibly datacompression

SAN Topology and Fiber Channel (FC) Technology (Cont.)

SAN topology consists of 3 different types: point to point, loop and fabric switch connection

SAN Topology and Fiber Channel (FC) Technology (Cont.)

Point-to-point

Point to point topology is simple, direct connection between 2 nodes and future expansion in not predicted.

Maximum throughput is 200Mbps full duplex

SAN Topology and Fiber Channel (FC) Technology (Cont.)

Arbitrated Loop Fiber Channel (FCAL) Most commonly deployed due to its flexibility but it is

only limited to 127 attachments Bandwidth in FCAL is shared among other ports in

the network with the maximum bandwidth 100MBps An example 50 nodes on a 100MBps network would

evenly distributed to 2MBps per node

SAN Topology and Fiber Channel (FC) Technology (Cont.)

Fabric Switch (FS) Increase the aggregate bandwidth when additional

port is added in gigabit range Ideal component for WAN or in extended SAN

topology Can address up to 15 million unique identifiers Zoning allow segregation of devices by port or WWW number

SAN Topology and Fiber Channel (FC) Technology (Cont.)

Typical SAN configuration environment

Planning and Managing SAN

As SAN becomes more popular in the enterprise networks, fabrics composed of multiple switches will become more common place

Show case application, such as full motion video editing and high performance relational data base servers and many data centers are already driving large fabric configurations

According to Strategic Research Corp., a storage consulting firm, 80% of most servers today are SCSI or IDE

So what storage can be migrated to SAN and how to manage it?

Proper planning...

Planning and Managing SAN (Cont.)

Considering these questions when your are planning for SAN:

What data and applications warrant the added cost and complexity of a SAN?

What storage should remain on less costly server-attached RAID?

What kinds of user activity can be expected? How much capacity should each SAN partition have? Which SAN partitions should be more than one

server share for failover?

Planning and Managing SAN (Cont.)

SAN would definitely be beneficial to these areas:

Mission-critical applications as the most obvious candidates for SAN migration

Transaction processing, e-mail, Groupware, ERP, multimedia file serving, and database serving as applications that can benefit most from hosting their storage on SAN, due to its advantages in performance, availability, and data protection

What about managing SAN?

Planning and Managing SAN (Cont.)

Storage Virtualization There are software packages and resources

available to manage SAN. A single concept behind those packages has driven SAN to this date is the storage virtualization

Through storage virtualization an organization is able to create a single view of its storage systems

With out storage virtualization it’s impossible to take full advantages of SAN.

“Virtualization is the holy grail of SANs” according to Netconvergence Inc.

These are companies carry resource managing packages: IBM (Tivoli), Sun (SRM), Veritas (Sandpoint)…and many others

Management Perspective

Many IT managers are looking at different ways approaching SAN in terms of costs and SAN's manageability.

According to Ian Mount of www.ecompany.com “Users relied on the server to get the data they requested; if the server was down or busy with other things, they'd have to wait. Companies that wanted more storage space had to buy more servers, and as more data clogged the networks, they needed faster, cheaper, and more easily managed approaches.”

Buying more servers and data clogged the network are the keywords when making decisions to migrate to SAN...

Management Perspective (Cont.)

And those decisions are based on the current conditions, the applications, and feasibility of the network infrastructure

To reduce the long-term costs IT managers should also look into the overall benefit of SAN such as the greater application availability, better application performance, practical data movement, and centralized storage.

Management Perspective (Cont.)

Centralized Storage: By providing the means of storage consolidation, SAN delivers greater scalability, reliability, flexibility, and serviceability.

Greater Availability: Because of no single point failure data can be accessed through alternate paths in cluster environment.

Better Application Performance: No overhead on the primary LAN due to separate subnet design and it's server independent. It has no limitation on the sever

Practical Data Movement: SAN enables cost-effective implementations of high availability, disaster protection configurations, like remote clusters, and mirroring

Management Perspective (Cont.)

SAN issues and benefits

Conclusions

Yesterday I used a SAN that wasn’t there. It wasn’t there today. I wish

that SAN would go away.” By Doug Pryor, Server/Workstation Expert Magazine.

SAN is not going anywhere as the matter of fact it’s gaining more speed everyday.

According to IDG by 2003, 48% in the area of storage array are for SAN. NAS will reach to 23%, and and traditional disks attaching directly to servers is at 29%.

In order to take full advantage of SAN one should keep in mind that preemptive is the keyword as part of solving business problem in order to keep it in operation 24/7.

Focus in Reliability, Availability, and Serviceability

Conclusion (Cont.)

According to IDG almost 80% of the major outages in the data center are caused by the process and the people.

So when you are planning, implementing, and managing SAN make sure to keep these numbers in mind and think preemptive .

Additional information

How to design a SAN http://www.storage.ibm.com/ Network storage solutions http://www.sun.com/storage/san/