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- 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,
- 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).