Snapshots in ZFS aren’t cumulative. They just include the difference between the filesystem at the time you took the snapshot and now.
Meaning if you have snapshots A, B and C, deleting A doesn’t impact the status of the remaining B and C. This is a common point of confusion when coming from other systems where you might have to consolidate snapshots to get to a consistent state.
This means, you can delete snapshots out of the middle of a list and not screw up snapshots before or after the one you deleted. So if you have:
pool/dataset@snap1 pool/dataset@snap2 pool/dataset@snap3 pool/dataset@snap4 pool/dataset@snap5
You can safely
sudo zfs destroy pool/dataset@snap3 and 1, 2, 4, and 5 will all be perfectly fine afterward.
You can estimate the amount of space reclaimed by deleting multiple snapshots by doing a dry run (-n) on
zfs destroy like this:
sudo zfs destroy -nv pool/dataset@snap4%snap8 would destroy pool/dataset@snap4 would destroy pool/dataset@snap5 would destroy pool/dataset@snap6 would destroy pool/dataset@snap7 would destroy pool/dataset@snap8 would reclaim 25.2G
List your snapshots (for a specific dataset simply use grep):
sudo zfs list -rt snapshot | grep pool/dataset
If you need to free some space, you can sort zfs snapshots by size:
zfs list -o name,used -s used -t snap