VSS Error EventID: 8193 from the Event Log (under construction)


Problem

Sometimes, when you perform a backup it stops in a few minutes or even right after the start with the following error message: "The provider returned an unexpected error code".

The research of the log files gives more details about this fail but the issue remains unclear

VSS Error 12/7/2018 8:23:12 AM EventID: 8193 Volume Shadow Copy Service error: Unexpected error calling routine Cannot find anymore diff area candidates for volume \?\Volume{ae7c3d9e-5755-11e1-9069-806e6f6e6963}\ [0]. hr = 0x8000ffff, Catastrophic failure.

Operation: Automatically choosing a diff-area volume Processing EndPrepareSnapshots

Context: Volume Name: \?\Volume{ae7c3d9e-5755-11e1-9069-806e6f6e6963}\ Volume Name: \?\Volume{ae7c3d9f-5755-11e1-9069-806e6f6e6963}\ Execution Context: System Provider

The VSS (Volume Shadow Copy Service) is a technology that provides the ability to create a point in time snapshot (or a shadow copy) to perform a backup of one or more volumes even when they are in use.

Suggestions and Resolutions

Increase the shadow copy storage area for the volume listed in the error event, or set the maximum size to “No limit.”

To identify the volume listed in the event, run “mountvol” from a command prompt; below the usage information will be a list of volume GUIDs and their associated mount points, if any.

This size of the shadow storage area can be changed in the Shadow Copies utility, or from the command line.

Shadow Copies Utility (Server OS Only)

To access the utility, right click any volume and choose Configure Shadow Copies. On older server operating systems, this may instead be a tab in Properties. In the Shadow Copies utility: Select the volume with insufficient space; Click Settings… In the “Maximum size” box, either increase the limit, or choose “No limit”.

Command Line (Client or Server OS)

All commands below should be run from an administrator command prompt.

Use

vssadmin list shadowstorage 

to view existing shadow storage associations. If no association exists for any volume, the command response will be “No items found that satisfy the query.”

Note: When no shadow storage association exists for a volume, the shadow copies utility will display 10% of the volume or MinDiffAreaFileSize, whichever is greater. However, Windows may set a different maximum size during shadow copy creation. While the default behavior works well for most volumes, setting a limit of 15-20% of the total volume size may be needed on busy servers.

If no association is listed for the volume, run

vssadmin add shadowstorage 

to set the size of the shadow storage area. For example, on a 1 TB volume labeled D:

vssadmin add shadowstorage /for=D: /on=D: /maxsize=200GB

If a shadow storage association already exists, run vssadmin resize shadowstorage to set the size of the shadow storage area. For example, on a 1 TB volume labeled D:

vssadmin resize shadowstorage /for=D: /on=D: /maxsize=200GB

The /maxsize parameter is not optional, but can be set as /maxsize=UNBOUNDED