modifyhd --resize should warn users about existing snapshots

[Lillo]

When resizing an existing VM using vboxmanage modifyhd vm.vdi --resize 12345 a user should be warned if the VM to be resized has unmerged snapshots. Since neither the documentation nor the vast majority of tips on the internet mention this problem, a user will *naturally* run the command above on what they believe to be *the* associated VDI file, *not* on one of the snapshots.

Consequently, modifyhd should first check whether the VM in question uses unmerged snapshots and issue a warning if so.

A perfect solution would have modifyhd determine the latest snapshot and offer the user to resize that snapshot instead.

[Perry G]

Replying to Lillo:

A perfect solution would have modifyhd determine the latest snapshot and offer the user to resize that snapshot instead.

AFAIK Snapshots are differencing disks and as such are not supported for resizing. At least that is the error message reported when trying, so it would make no sense to suggest resizing them.

However it would be a great idea to make notice in the User Manual stating this as a lot of people try and fail.

[robert@…]

+1

This should be closed as duplicate of #9103, or at least of #13046, which has a more detailed description of the problem.

(Can someone add me to Cc please? It seems I can't do this myself.)