Backup completes with the exception "An unexpected error occurred when cleaning up snapshot volumes" when the resource backed up contains a volume larger than 64TB.

Problem

Backup completes with the exception when the system being backed up contains a volume larger than 64TB.

This occurs even if the volume is not a part of the resources being backed up.

Error Message

V-79-57344-34108 - An unexpected error occurred when cleaning up snapshot volumes. Confirm that all snapped volumes are correctly resynchronized with the original volumes.

or

V-79-10000-11223 The Microsoft Volume Shadow Copy service (VSS) that you selected cannot snap this volume. Select the default snapshot provider, and then run the job again

Cause

As documented in the Microsoft article https://docs.microsoft.com/en-US/troubleshoot/windows-server/backup-and-storage/usability-limit-volume-shadow-copy-service  VSS (Volume Shadow Copy Service) has a usability limit of 64TB. As Backup Exec will generally attempt to take a VSS snapshot during a backup job, if the system being backed up contains a volume larger than 64TB, the backup will complete with this exception message.

Note: This occurs even if the following registry key has already been added to resolve the issue discussed in Windows System State backup fails if any mounted volume's capacity is greater than 63,000,000,000,000 bytes (57.3 TB)

HKLM\SOFTWARE\Veritas\Backup Exec For Windows\Backup Exec\Engine\Misc\BescLargeDiscBlock

Solution

To ensure that all backup jobs are able to use VSS snapshots successfully, Veritas recommends no volume larger than 64TB exists on any system that requires backing up.

Post Creation of the Registry key the job will complete with and Exception Only:

V-79-10000-11217 - VSS Snapshot error. The Microsoft Volume Shadow Copy Service (VSS) snapshot failed. Make sure that all provider services and tasks are running. Check the Windows Event Viewer for details.

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