What happens to VSS (system restore points), when drives are moved to a new installation.

So a bit of background to be sure what we talking about.

System restore can be used on data drives, when a restore point is made, it creates a volume snapshot, which allows the operator of the machine aka myself, to restore files/folders from that snapshot whenever I want, there is even support for this in the explorer properties box, where it says previous versions of files.

The reason I am making this post, is I have discovered if a drive has volume snapshots aka system restore points, and its mounted in a new Windows installation so eg. creating the VSS in Windows 10, then installing Windows 11, all of the volume snapshots are gone, they dont exist.

But logically they surely still exist, as its an operation carried out on the partition's filesystem itself, one of the downsides of using these snapshots, is whenever the data is changed on the drive, there is a storage overhead to maintaining the snapshot as the old data is effectively protected from deletion, which is how it stays accessible.

I believe the reason they go invisible, is there is a global restore point index that is stored at the OS level, so this is lost on a OS change, I noticed e.g. if a restore point is wiped on C: due to space constraints, then it also gets wiped on all data drives, So there is a requirement of linking snapshots on data drives to matching snapshots on the C: drive, presumably as the way system restore is designed (it is possible to create independent VSS outside of system restore, I just dont do it this way as its more manual work, system restore auto manages the space overhead for you).

So my question is, these snapshots, do they remain on the drive forever with a permanent overhead, but simply invisible in the new OS, or does NTFS have some cleanup mechanism, so perhaps e.g. when you configure system restore on the drive in the new OS, does it then detect all the old ones and clean them up?

I would appreciate if anyone knows the answer to this, I am dual booting, so what I can probably do is boot back into Windows 10, manually disable system restore on all the data drives, and delete all of the VSS data as well, which effectively should clean it up, and then reconfigure it on 11 moving forward, but an anaswer would be appreciated regardless.

Snapshot overhead for System Restore volumes is only saved on the Windows system drive. When you move any drive to another system, none of that overhead is transferred over. The new system can detect the old VSS snapshots, but there isn't a built-in mechanism to import or recover them.

In short, System Restore isn't designed for portability. On the new system, Windows will not continue updating the snapshots, nor will it clean them up. Because there are no VSS writers configured for that volume.

You have to manually delete the snapshots in vssadmin, to recover your disk space.