using volsnap/VSS with non-NTFS filesystems

NTFSD
1

Has anyone managed to support Volume Shadow Copies to snapshot non-NTFS volumes? I'd really like to use it for snapshotting, but VSS appears to require NTFS (not even FAT) to work; "vssadmin list volumes" only shows NTFS volumes.

"How Volume Shadow Copy Service Works" (circa 2003) at How Volume Shadow Copy Service Works: Data Recovery | Microsoft Learn got my hopes up:

For the system provider, the shadow copy storage area must be on an NTFS volume. The volume to be shadow copied does not need to be an NTFS volume, but at least one volume mounted on the system must be an NTFS volume.

I was hoping that all I'd need to do was implement IOCTL_VOLSNAP_FLUSH_AND_HOLD_WRITES, and VSS would magically start working--but it appears to not be quite that simple.

Some thoughts...

  • Is there some trick to get VSS to present non-NTFS volumes?
  • Would it make sense/be possible to implement another software provider that exposes the desired volumes? (Should I look more that the VSS SDK?)
  • Are the interfaces to the volsnap storage filter documented? (Maybe it's possible to interface with it directly?)

Any ideas would be appreciated.

Thanks,
Jeff

2

I did find the answer to my own question. The updated documentation at

has a FAQ:

Can VSS create shadow copies of non-NTFS volumes?
Yes. However, persistent shadow copies can be made only for NTFS volumes. In addition, at least one volume mounted on the system must be an NTFS volume.

Which is great--I didn't realize that nonpersistent shadow copies are what I'm looking for.

Jeff