Egregoros

ZFS fun at work today. `zfs rollback` is very very slow. What turned out to be 1000x faster was:
* delete all intermediate snapshots
* zfs rename badfs badfs-bad
* zfs clone badfs-bad@good-snapshot badfs
* zfs promote badfs
* zfs destroy -r badfs-bad

My guess is that `zfs rollback` is synchronous and we were stuck waiting for the blocks to be freed before it would return. (I chose an intermediate snapshot as the first rollback target just in case, and it took about 45 minutes.)