Windows Server 2016 VSS System Requirements - Additional Disk?

Question

I have a Windows 2016 server I'd like to set up Volume Shadow Service (VSS). Is it still recommended that I have a separate physical disk?

The setup dialog itself seems to state this as you see in the link below:

Am I missing something? Microsoft's own documentation doesn't do a great job at detailing the requirements.

If your shadow copies are on the same disk and the disk dies, what are you going to do? — joeqwerty, May 20 '20 at 20:29
@Swisstone Yes, during the day. If I put in on the same volume, can I just schedule it for hours when the server is sitting idle (nighttime/early AM)? — user777958, May 31 '20 at 14:56
Can 2 volumes with VSS enabled share same 'storage area' on a dedicated VSS disk? — user777958, Jun 04 '20 at 18:23

score 2 · Answer 1 · answered May 21 '20 at 08:34

VSS (Volume Shadow Copy Service, or Volume Snapshot Service), is a technology included in Microsoft Windows that allows taking manual or automatic backup copies or snapshots of computer files or volumes. The VSS captures and copies stable images for backup on running systems, particularly servers, without unduly degrading the performance and stability of the services they provide. This happens completely transparent to the overlaying NTFS.

By default, VSS shadow copies are saved onto the drive they are copying. However, you may want to save your VSS shadow copy to a different drive, perhaps one with greater capacity or redundancy.

On fileservers with high load on its disks, the additional I/O of keeping snapshots may impact performance (significantly).

In usual everyday-fileservers with a few users (~300 Users if your I/O ist reasonably fast), keeping it on the same volume may not be any problem. In todays virtualized environments, disk redundancy is no longer the guest operating systems problem.

Rule of thumb: VSS on the same disk is a lot better than no VSS at all - as long as you don't feel any performance problems (which is rare).

Thanks! This is a small office of <50 users the core applications during the day are high load on the disks. Can't I just schedule the VSS snapshots for the end of the day or early morning? Would this solve it? I'm using VSS for backup and don't care if users can restore copies. I wish MSFT had more documentation on this feature... TIA! — user777958, May 31 '20 at 14:53
Rule-Of-Thumb: As long as your disk makes <30mb/s, just do your vss whenever you want. It depends more on what snapshots you need, than when you can do them. — bjoster, Jun 01 '20 at 20:03

score 0 · Answer 2 · answered Jan 03 '23 at 16:39

A physical disk helps a lot with overall performance, but is far from necessary as long as your RAID hardware is up to snuff. If it's not, you'll find out by orphan shadows building up in the hidden and highly protected System Volume Information folder on the volume. To find out if it's building up, run a disk space usage checker which is capable of seeing that folder, many aren't. SpaceSniffer is, it still works on current OS even though it has not been updated in a while. Clearing orphan shadows, unfortunately, means clearing your "backup" shadows as well, which would be quite problematical if that were used as general backup.

Windows Server 2016 VSS System Requirements - Additional Disk?

2 Answers2