I have a small system with two drives running Solaris 11 with a ZFS mirrored root pool. I need to enlarge the root pool. Can I just install two large drives, one at a time, waiting for each one to resilver? Or will the first replacement disk have it's extra space ignored forever? I know there is a property called "autoexpand", but I'm not sure how that applies in a mirror situation.
Yes, you can enlarge a pool by zpool replace'ing the disks one-by-one with larger ones. One possible gotcha is that you'll need to install grub on your non-boot disk so that you can boot the system when you're replacing the disk you normally boot from. Also, you may need to change the boot order in the bios.