SAN Virtualization

• As SANs grow, it is hard to manage them - knowing which host uses which LUNs. It is also hard to perform backups in today's environment, where you can't afford down-time for backup purposes (and you can't backup an active file-system).
• RAIDs were the first to virtualize things - virtual disks, snapshots, mirroring...
• Reliance on the applications in the high-end RAIDs result a vendor lock-in - which mean high prices.
• For starters, LVM (Logical Volume Management) in the hosts allow performing snapshots in the hosts rather then in the RAID - but then you cannot access these snapshots via another host.
• There is growing tendency to move all this virtualization to the network level - where you allow sharing snapshots and virtual volumes between hosts, have centralized management, and can mix RAIDs from different vendors (and thus reduce RAID prices).

Originally written by guy keren