[Feature request] Protect last x number of snapshots

[ayakael]

When using syncoid, or other send-based backup solution, the last snapshot is used to calculate the delta to send an incremental stream. Using your script in that application would run the risk of destroying snapshots that zfs send/recv needs for incremental backup. It'd be nice if there was a feature to protect the last x number of snapshosts as to ensure their existence regardless of time cut-off point.

[joltcan]

And also to make sure that there is always a remaining copy on the remote host if this is needed (i.e. because I'm paranoid)

[bahamas10]

👍 i'm all for adding a protect feature. @joltcan that is a good idea but anything remote is outside the scope of what zfs-prune-snapshots should do imo

[joltcan]

Forget the remote part, that is only one use-case. Regardless I would prefer being able to have X copies left as a failsafe.

[mikebakke]

Additional vote (as if required) for protect option. I am a newb with ZFS and am simultaneously in awe of the benefits it brings and abject terror at the ease with which data can be lost by the user doing something they really don't fully understand :-)

[fernsehmuell]

+1 this should also be the default (never delete ALL snapshots, keep the latest, so you can do differential backups). If you really want to delete all of them use a flag like -f.