Replication breaks if dataset quota reached

[Johnny Fartpants]

I’ve seen this a lot over the years from even the earlier FreeNAS days so it’s not a new issue. In my experience when a replication pair is created if a dataset hits 100% of its quota then replication fails as the receiving end doesn’t have enough space to accommodate the recent snapshot changes (no matter how small). It appears that zfs send wants to pass over the changes (most recent snaps) before purging the old snapshots meaning that the receiving end will always need a bit more space then the sender to prevent this error from happening. The fix is simple just increase or remove the quota from the receiving end and replication works again however it’s a bit of a pain.

I wonder if by default the receiving dataset quota could always be something like 1% larger than the sender to reduce the likelihood of this happening?

I’d be interested to hear your thoughts and if this is something anyone else has experienced before?