FSRM: The shadow copy storage area should be large enough for File Server Resource Manager to create snapshots of files

Published: April 27, 2010

Updated: August 4, 2010

Applies To: Windows Server 2008 R2, Windows Storage Server 2012

This topic is intended to address a specific issue identified by a Best Practices Analyzer scan. You should apply the information in this topic only to computers that have had the File Services Best Practices Analyzer run against them and are experiencing the issue addressed by this topic. For more information about best practices and scans, see Best Practices Analyzer.


Operating System

Windows Server 2008 R2


File Services





The shadow copy storage area (also known as the VSS diff area) is too small to create snapshots of files during the process of running file classification rules, creating storage reports, or performing file management tasks.

When File Server Resource Manager creates a snapshot of an open file, it could overwrite existing shadow copies and possibly fail to classify files, create storage reports, or execute file management tasks because of insufficient disk space.

Use the Vssadmin.exe command-line tool to increase the size of the shadow copy storage area.

The command vssadmin resize shadowstorage resizes the maximum size for a shadow copy storage association between <ForVolumeSpec> and <OnVolumeSpec>. The syntax is as follows:

vssadmin resize shadowstorage /for=<ForVolumeSpec> /on=<OnVolumeSpec> [/maxsize=<MaxSizeSpec>]

Following is an example command:

vssadmin resize shadowstorage /for=C: /on=D: /maxsize=900MB

Resizing the storage association may cause shadow copies to disappear. If you do not specify MaxSizeSpec, there is no limit to the amount of space it can use. As certain shadow copies are deleted, the shadow copy storage space will shrink. MaxSizeSpec must be 1 MB or greater, and it accepts the following suffixes: KB, MB, GB, TB, PB, and EB. If a suffix is not supplied, MaxSizeSpec is represented in Megabytes.

  1. To open an elevated Command Prompt window, click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.

  2. At the command prompt, type: vssadmin add shadowstorage /for= <ForVolumeSpec> /on= <OnVolumeSpec> [/MaxSize=<MaxSizeSpec>]

Vssadmin (http://go.microsoft.com/fwlink/?LinkId=199587)

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