IBM Tivoli Storage Manager for Mail, Data Protection for Microsoft Exchange Server, Version 7.1

Thin provisioning support

Thin provisioning or the ability to allocate less physical storage than the declared size of a logical storage volume is available with supported hardware. A thinly provisioned volume is referred to as a space-efficient (SE) volume.

The complete list of supported hardware for a space-efficient FlashCopy is available online at http://www.ibm.com/support/docview.wss?uid=swg21455924.

SAN Volume Controller and Storwize® V7000 provide FlashCopy® restore from SE target volumes and from fully allocated target volumes for which the background copy of the VSS backup is not yet completed. In addition, the hardware supports a restore from fully allocated target volumes for which the backgroud copy of the VSS backup has completed. You can retain multiple FlashCopy images of a source volume as backup generations at a much reduced storage cost. You do not have to allocate the full size of the source volume for each backup generation.

For SE target volumes, the SAN Volume Controller and Storwize V7000 hardware architectures minimize the space that is required to maintain multiple snapshots of the same source volume. Target volumes are placed into a cascade where each target is dependent on changes that are recorded in target volumes of subsequent snapshots. For example, assume that four VSS snapshots are created of a source volume. S is the source and T1 through T4 are the targets. T1 is the first, chronologically, and T4 is the last. The following cascade occurs:

S -> T4 -> T3 -> T2 -> T1

With this type of cascade relationship, a copy-on-write process is needed only between the source volume and the latest FlashCopy target. Any blocks that remain unchanged on the source volume are not copied at all. However, the cascaded relationship, where multiple SE target volumes have the same FlashCopy source, requires some special considerations when you use the target volumes as backup versions managed by Data Protection for Exchange.

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