Tim Connors wrote: I am using ZFS for a package repository which is mounted inside the jail or host system I want to upgrade (it's part of a script which can do that on the fly for all jails+host when needed) Transfer between hosts happens via zfs send/receive. Having one mountpoint at the time solves the "two at the time" problem - and scripting others (e.g. the right repository for the right system). I can imagine similar usage when using Linux and btrfs. Regards Peter