RandalSchwartz: yeah, and I use a similar method to resize just regular UFS partitions (must be last partition, as you said)
One of the nice things about adding the space as a second vdev is, if you can attach the storage to a running VM, ZFS can start using the additional space without needing a reboot.
wow nice
The "attach storage to a running VM" is something most hypervisors can't do. :/
But yeah, no-reboot storage expansion is awesome.
On my real-metal servers, I mimic RAID 10 in ZFS and can expand storage by adding pairs (or trios, for the N+2 systems) of disks.
pilgrimd: xen can do