NetAPP ASIS De-Duplication for unstructured data

de-duplication work on common block on same aggregate and thats why
its most suitable for backup storage where we need multiple version
and lots of common blocks happen.

While that is completely correct, NetApp is also trying to make the case
that there are some primary storage scenarios that also have a lot of
duplicate data. While you won't see 20:1 you might see 4:1. If you can
have 4:1 and it's FREE (since they don't charge for dedupe), and it
doesn't have any performance impact (since they leverage WAFL), then it
doesn't hurt to have it on primary either. One example I've heard them
give is vmware virtual desktop images. If you add vmware snapshots to
that (which is a backup scenario), it gets even better.

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W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies