Categories: XenServer, Physical Systems, Hyper-V, Alike v3

Introduction

Alike fails during a Q-Hybrid backup/replication job with the error:

• “VSS snapshot is no longer available”

or

• “Waited, but device does not exist”

Learn why this problem can occur and how to resolve it in this KB article.

Common Causes

This problem occurs when the VSS snapshot being used for a backup or replication job by Alike is removed while the job is still processing. The most common cause of this problem is that the VSS ShadowStore ran out of space due to I/O on the live filesystem while the Alike job was in process, and Windows removed the VSS snapshot(s) to reclaim space.

Resolution

To avoid this problem, you can increase the space available for VSS shadow storage, or perform your backups during a less active time of the day.

To check your system’s shadow storage space, you can run the vssadmin command:

• “vssadmin list shadowstorage”

Example output:

• vssadmin 1.1 – Volume Shadow Copy Service administrative command-line tool

C) Copyright 2001-2005 Microsoft Corp.

For volume: (C: )\\?\Volume{3ce0cbe3-57c2-11db-a712-806e6f6e6963}\ Shadow Copy Storage volume: (C: )\\?\Volume{3ce0cbe3-57c2-11db-a712-806e6f6e6963}\

• Used Shadow Copy Storage space: 13.012 GB
• Allocated Shadow Copy Storage space: 13.116 GB
• Maximum Shadow Copy Storage space: 14.649 GB

In the case above, this system has very little space available for VSS snapshots. If you encounter this error, increasing the shadow store size may eliminate this problem.

Final Notes

To resize your shadow storage, you can also use the vssadmin tool. For example, to raise your C:\ storage to 50GB, you would enter:

• “vssadmin resize shadowstorage /for=C: /on=C: /maxsize=50GB”