PSARC/2009/511 zpool split have integrated into upcoming ON build 131. This feature will make it easier to split off mirrored disks as a new pool and use it somewhere else or lock it away. This operation have been a quite common operation when using volume managers and some people seem to have missed this in ZFS.
From the PSARC:
Some practices in data centers are built around the use of a volume manager's ability to clone data. An administrator will attach a set of disks to mirror an existing configuration, wait for the resilver to
complete, and then physically detach and remove those disks to a new location.
Currently in zfs, the only way to achieve this is by using zpool offline to disable a set of disks, zpool detach to permanently remove them after they've been offlined, move the disks over to a new host, zpool force-import of the moved disks, and then zpool detach the disks that were left behind.
This is cumbersome and prone to error, and even then the new pool cannot be imported on the same host as the original.
Introduce a "zpool split" command. This will allow an administrator to extract one disk from each mirrored top-level vdev and use them to create a new pool with an exact copy of the data. The new pool can then be imported on any machine that supports that pool's version.
Talks I have given
2 weeks ago