It sounds like you are getting a good plan together. > The only thing though I seem to remember reading that adding vdevs to > pools way after the creation of the pool and data had been written to it, > that things aren't spread evenly - is that right? So it might actually make > sense to buy all the disks now and start fresh with the final build.
In this scenario, balancing would not impact your performance. You would start with the performance of a single vdev. Adding the second vdev later will only increase performance, even if horribly imbalanced. Over time it will start to balance itself. If you want it balanced, you can force zfs to start balancing by copying files then deleting the originals. > Starting with only 6 disks would leave growth for another 6 disk > raid-z2 (to keep matching geometry) leaving 3 disks spare which is > not ideal. Maintaining identical geometry only matters if all of the disks are identical. If you later add 2TB disks, then pick whatever geometry works for you. The most important thing is to maintain consistent vdev types, e.g. all RAIDZ2. > I do like the idea of having a hot spare I'm not sure I agree. In my anecdotal experience, sometimes my array would offline (for whatever reason) and zfs would try to replace as many disks as it could with the hot spares. If there weren't enough hot spares for the whole array, then the pool was left irreversibly damaged, having several disks in the middle of being replaced. This has only happened once or twice and in the panic I might have handled it incorrectly, but it has spooked me from having hot spares. > This is a bit OT, but can you have one vdev that is a duplicate of > another vdev? By that I mean say you had 2x 7 disk raid-z2 vdevs, > instead of them both being used in one large pool could you have one > that is a backup of the other, allowing you to destroy one of them > and re-build without data loss? Absolutely. I do this very thing with large, slow disks holding a backup for the main disks. My home server has an SMF service which regularly synchronizes the time-slider snapshots from each main pool to the backup pool. This has saved me when a whole pool disappeared (see above) and has allowed me to make changes to the layout of the main pools. -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
