Yes, that looks pretty good mike. There are a few limitations to that as you add the 2nd raidz2 set, but nothing major. When you add the extra disks, your original data will still be stored on the first set of disks, if you've any free space left on those you'll then get some data stored across all the disks, and then I think that once the first set are full, zfs will just start using the free space on the newer 8.
It shouldn't be a problem for a home system, and all that will happen silently in the background. It's just worth knowing that you don't necessarily get the full performance of a 16 disk array when you do it in two stages like that. Also, you mentioned in an earlier post about dual parity raid. Raid-z2 is very different from raid-z1, and it's not just a case of having a hot spare. Having the ability to loose two drives before data loss makes a massive difference to your chance of experiencing data loss. The most dangerous period on a raidz (or raid-5) pool is after a drive fails, when you're rebuilding the data onto a new disk, and with larger drives the risk is increasing. While you're rebuilding the array, your data isn't protected at all, but you're having to re-read all of it in order to populate the new disk. Any errors during that read will result in data corruption at best, and a dead raid array at worst. With drives getting bigger, the chances of an error are increasing. From memory I think it's something around a 10% chance of an error for every 5TB you're rebuilding. Of course, that could well be just a single bit error, but I've seen a fair few raid-5 arrays die and experienced a couple of near misses, so I'm very paranoid now when it comes to my data. Ross This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
