You may notice that after running a backup with enabled VSS option in the advanced backup settings, an active/enabled "Generic volume shadow copy" is left in Windows Device Manager under the "Storage volume shadow copies" section.
At the same time, the shadow copy in question does not appear in the output of the "vssadmin list shadows" command in the elevated commmand prompt.
Devices under "Storage volume shadow copies", among others, are created and controlled by Windows through volsnap.sys driver and Microsoft Software VSS Provider. They are related to, but are not the volume shadow copies that Acronis True Image interacts with.
Acronis True Image interacts with Microsoft VSS exclusively through VSS API. It has no direct access to the volume shadow copy devices displayed in the Windows Device Manager console.
Some of the VSS API is exposed through vssadmin command-line tool. You can use it to verify if Acronis True Image's behavior was expected and correct or not.
- Before starting the backup with the command "vssadmin list shadows" in the elevated command prompt, note the creation date of the last created shadow copy.
- Launch the backup task. If the VSS option is enabled in the advanced backup options, a temporary shadow copy will be created.
- When the backup finishes, the temporary shadow copy is deleted.
- Check the creation date of the newest existing shadow copy with "vssadmin list shadows"command again. It should not be newer than what you saw in step 1.
- If Acronis True Image backup task completes and the command "vssadmin list shadows" does not reveal any newer shadow copy, the behavior of Acronis software is expected and correct.
- If the new shadow copy remains in the "vssadmin list shadows" output even after backup task completion, use the free Acronis VSS Doctor to automatically find and fix common problems with VSS. If the issue persists, please contact Acronis Support for further investigation.