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ImportSnapshots operations in FlashCopy Manager local backup

Question & Answer


Question

Why are VSS ImportSnapshots calls performed during FlashCopy Manager for Windows VSS local backup?

Cause

FlashCopy Manager, working as a VSS requester during a local backup, will perform ImportSnapshots a couple of times.

Answer

When IMPORTVSSSNAPSHOTSONLYWhenneeded option is set to "Yes", transportable snapshots are created. For this type of snapshot, the ImportSnapshots operation is mandatory according to the Microsoft's processing of a backup under VSS. When ImportSnapshots is called, the VSS Hardware Provider will perform the LocateLuns process. During LocateLuns, the provider should make those shadow copy LUNs visible to the FlashCopy Manager for the Windows system. Thereafter, VSS will then rescan and perform the enumeration to allow the LUNs to be discovered by PNP and the volumes to come online. When the backup completes, the shadow copy LUNs are masked via the MaskLuns call.

When the IMPORTVSSSNAPSHOTSONLYWhenneeded option is set to "No", FCM will create NON-Transportable snapshots. The import calls are still made because it uses Auto Import, so the snapshots are imported as well. When the backup completes, the shadow copy LUNs are not masked.

Additionally, during the reconciliation process to delete all snapshots eligible for expiration based on policy, the shadow copy LUNs are also imported and masked. So FlashCopy Manager has no option or setting that will prevent FlashCopy Manager from importing or importing/masking the snapshots.

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Product Synonym

FCM

Document Information

Modified date:
17 June 2018

UID

swg21969479