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IVssHardwareSnapshotProvider::OnLunEmpty method (vsprov.h)

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The OnLunEmpty method is called whenever VSS determines that a shadow copy LUN contains no interesting data. All shadow copies have been deleted (which also causes deletion of the LUN.) The LUN resources may be reclaimed by the provider and reused for another purpose. VSS will dismount any affected volumes. A provider should not issue a rescan during OnLunEmpty. VSS will handle this cleanup.

Note  Hardware providers are only supported on Windows Server operating systems.
 

Syntax

HRESULT OnLunEmpty(
  [in] VSS_PWSZ            wszDeviceName,
  [in] VDS_LUN_INFORMATION *pInformation
);

Parameters

[in] wszDeviceName

Device corresponding to the LUN that contains the shadow copy to be deleted.

[in] pInformation

Pointer to a VDS_LUN_INFORMATION structure containing information about the LUN containing the shadow copy to be deleted.

Return value

This method can return one of these values.

Return code/value Description
S_OK
0x00000000L
 The operation was successfully completed.
E_OUTOFMEMORY
0x8007000EL
 Out of memory or other system resources.
E_INVALIDARG
0x80070057L
 One of the parameter values is not valid.
VSS_E_PROVIDER_VETO
0x80042306L
 An unexpected provider error occurred. The provider must report an event in the application event log providing the user with information on how to resolve the problem.

Remarks

Hardware providers should delete a shadow copy and reclaim the LUN if and only if
OnLunEmpty is being called. A hardware shadow copy may be used as the backup media itself, therefore the LUNs should be treated with the same care the storage array treats LUNs used for regular disks. Reclaiming LUNs outside of processing for OnLunEmpty should be limited to emergency or an administrator performing explicit action manually.

In the case of persistent shadow copies, the requester deletes the shadow copy when it is no longer needed. In the case of nonpersistent auto-release shadow copies, the VSS service deletes the shadow copy when the requester calls IUnknown::Release on the IVssBackupComponents object. In the case of nonpersistent non-auto-release shadow copies, the VSS service deletes the shadow copy when the computer is restarted. In all cases, the VSS service calls the provider's OnLunEmpty method as needed for each shadow copy LUN.

Note that OnLunEmpty is called on a best effort basis. VSS invokes the method only when the LUN is guaranteed to be empty. There may be many cases where the LUN is empty but VSS is unable to detect this due to errors or external circumstances. In this case, the user should use storage management software to clear this state.

Some examples:

  • When a shadow copy LUN is moved to a different host but not actually transported or imported through VSS, then that LUN appears as any other LUN, and volumes can be simply deleted without any notification of VSS.
  • A crash or unexpected reboot in the middle of a shadow copy creation.
  • A canceled import.

Requirements

Requirement Value
Minimum supported client None supported
Minimum supported server Windows Server 2003 [desktop apps only]
Target Platform Windows
Header vsprov.h

See also

IVssHardwareSnapshotProvider