Replacing all disks in zroot

[Malcolm Matalka]

Hello,

Right now I have a ZFS on root on FreeBSD 10.3.  Currently I only have 1
disk in zroot and it's too small.  So I would like to do the following
thing, but I'm not sure if I need to do some special work to make the
new setup bootable.

1. Bought 2 new, larger HDs.

2. Going to add one of them to the existing disk as a mirror and let it
resilver.

3. Replace the small drive with the second drive I bought, removing the
smaller drive.

As I understand it, after this I will have the larger capacity,
mirrored.  But will this be bootable?  Do I have to do something else to
copy the boot setup over?

Thanks,
/Malcolm