October 2001

ITSS SAN Purchase
In June of 2001, ITSS invested in a Storage Area Network (SAN) to provide faster and more reliable disk storage for the Office and Lab servers. A SAN is essentially a pool of disk drives that can be partitioned and allocated to one or more computer systems (typically a server). The computer or server doesn't use a particular physical disk, but instead uses what is called a virtual disk. The virtual disk is written to many physical disks behind the scenes. As far as the computer or operating system is concerned, it only sees what it thinks is a large disk drive. The SAN is typically connected to a server by fiber optic cables and a special Fiber Channel interface that goes into each server.

A SAN offers many advantages over traditional local attached storage. The disk pool can be increased in size during production hours by simply adding more disk drives or additional SAN cabinets (which hold the disk drives). Virtual disks can be allocated to servers, in many cases without having to schedule downtime for users. Many hardware components are redundant, so that if a power supply, cooling fan, or disk drive fails, another will take over. Most of these components are also hot swappable, so that replacement parts can be installed any time without shutting down the system. Finally, the SAN will work with almost any type of server or operating system, and can scale to extremely large sizes.

The only disadvantage to a SAN is that it is initially more expensive than traditional storage. However, the performance gains, scalablity, and management features balance out this cost over time. In turn, this means that the end user will experience less downtime due to server failures. In particular, the SAN eliminates the affect of disk drive failures, which is probably one of the most critical components of any computer system. Anyone who has lost data due to a disk drive failure will understand what this means.

If you are curious about how a SAN works and would like more information, feel free to contact Tim Biles (tbiles, 6959) and he will try to answer your questions.


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Last modified on 10/05/01
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