On Tue, April 13, 2010 09:48, Christian Molson wrote: > > Now I would like to add my 4 x 2TB drives, I get a warning message saying > that: "Pool uses 5-way raidz and new vdev uses 4-way raidz" Do you think > it would be safe to use the -f switch here?
Yes. 4-way on the bigger drive is *more* redundancy (25%, rather than 20%) (though not necessarily "safer", since the bigger drive increases recovery time) than 5-way on the smaller drive. I'd describe these as "vaguely" the same level of redundancy, and hence not especially inappropriate to put in the same pool. Putting a single disk into a pool that's otherwise RAIDZ would be a bad idea, obviously, and that's what that message is particularly to warn you about I believe. However, I have some doubts about using 2TB drives with single redundancy in general. It takes a LONG time to resilver a drive that big, and during the resilver you have no redundancy and are hence subject to data loss if one of the remaining drives also fails. And resilvering puts extra stress on the IO system and drives, so probably the risk of failure is increased. (If your backups are good enough, you may plan to cover the possibility of that second failure by restoring from backups. That works, if they're really good enough; it just takes more work and time.) 24 hot-swap bays in your home chassis? Now that does sound pretty extreme. I felt like my 8-bay chassis is a bit excessive for home; and it only has 6 bays populated with data-disks, and they're just 400GB. And I store a lot of RAW files from DSLRs on it it, I feel like I use quite a bit of space (until I see somebody come along casually talking about vaguely 10 times more space). How DO you deal with backup at that data size? I can back up to a single external USB disk (I have 3 I rotate), and a full backup completes overnight. -- David Dyer-Bennet, d...@dd-b.net; http://dd-b.net/ Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/ Photos: http://dd-b.net/photography/gallery/ Dragaera: http://dragaera.info _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
