SAN storage places the physical disk outside a computer system. It is now connected to a Storage Area Network (SAN). In a Storage Area Network, storage is offered to many systems, including AIX systems. This is done via logical blocks of disk space (LUNs). In the case of an AIX system, every SAN disk is seen as a seperate hdisk, with the advantage of easily expanding the AIX system with new SAN disks, avoiding buying and installing new physical hard disks.

• Disk storage is no longer limited to the space in the computer system itself or the amount of available disk slots.
• After the initial investment in the SAN network and storage, the costs of storage per gigabyte are less than disk space within the computer systems.
• Using two different SAN networks (fabrics), you can avoid having disruptions in your storage, the same as mirroring your data on separate disks. The two SAN fabrics should not be connected to each other.
• Using two seperate, geographically dispersed storage systems (e.g. ESS), a disruption in a computer center will not cause your computer systems to go down.
• When you place to SAN network adapters (called Host Bay adapters on Fibre Channel or HBA) in every computer system, you can connect your AIX system to two different fabrics, thus increasing the availability of the storage. Also, you'll be able to load balance the disk storage over these two host bay adapters. You'll need Multipath I/O software (e.g. SDD or PowerPath) for this to work.
• By using 2 HBAs, a defect in a single HBA will not cause downtime.
• AIX systems are able to boot from SAN disks.

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