VSS leftovers after image restore | comparison v4.9.5 vs. v5.0.0 beta

[admin]

Hey there,

I have a scheduled task that automatically runs a snapshot of c:\ twice a day. Command is:
wmic shadowcopy call create Volume='C:\'

Windows then stores these snapshots in C:\System Volume Information.
This enables the "Previous versions" feature in Explorer to be able to go back to an older version of a folder/file.

But what happens with those files on an image backup/restore scenario?

I tested different scenarios, here are the results:

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1. Image backup with HBS v4.9.5:

Behavior:
- All files in C:\System Volume Information are copied and kept in the image backup.
- On restore those files will be recreated but as empty 0-byte files.

Result:
- Restored Windows will not have Previous versions available in Explorer.
- No additional space is wasted in C:\System Volume Information.

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2. Image backup with HBS v5.0.0, VSS files filtered out (default):

Behavior:
- VSS files in C:\System Volume Information are NOT copied in the image backup.
- On restore those files are not available, no empty 0-byte files.

Result:
- Same as with HBS v4.9.5

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3. Image backup with HBS v5.0.0, VSS files NOT filtered out:

Behavior:
- VSS files in C:\System Volume Information are copied in the image backup.
- On restore those files are restored as well.

Result:
- Unfortunately Windows will NOT use those restored VSS files but still show 0 byte usage.
- Restored Windows will NOT have Previous versions available in Explorer.
- Those restored VSS files will be kept forever, resulting in less space available on C:\

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4. Image backup with Macrium Reflect v8.1.8311:

Behavior:
- Same behavior as scenario 2 (HBS v5.0.0 with VSS files filtered out)

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So what do these tests show exactly?

I think the default behavior of HBS v5.0.0 (scenario 2) is perfect, as those files are not backed up anymore. This is also the default in Macrium.
If you change that filter option in HBS v5.0.0 and you keep VSS files (scenario 3), this will result in permanently wasted space after restore.

(?) For scenario 3, Windows will not use those VSS files after a restore anyway. So if the user removes that filter option this should maybe trigger a warning for the user? Or maybe this option should not be removable at all?

If Windows could be somehow convinced to reuse those snapshots in scenario 3, this wouldn't be a problem at all. But this is probably impossible..?

Thank you for your suggestion, we will prevent users from removing this filter option until we find out why Windows is not reusing the restored VSS snapshot files.