> On Dec 21, 2009, at 4:09 PM, Michael Herf > <mbh...@gmail.com> wrote: > > > Anyone who's lost data this way: were you doing > weekly scrubs, or > > did you find out about the simultaneous failures > after not touching > > the bits for months? > > Scrubbing on a routine basis is good for detecting > problems early, but > it doesn't solve the problem of a double failure > during resilver. As > the size of disks become huge the chance of a double > failure during > resilvering increases to the point of real > possibility. Due to the > amount of data, the bit error rates of the medium and > the prolonged > stress of resilvering these monsters. > > For up to 1TB drives use nothing less than raidz2. > For 1TB+ drives use > raidz3. Avoid raidz vdevs larger than 7 drives, > better to have > multiple vdevs both for performance and reliability. > > With 24 2.5" drive enclosures you can easily create 3 > 7 drive raidz3s > or 4 5 drive raidz2s with a spare for each vdev, or 2 > spares and 1-2 > SSD drives. Both options give 12/24 usable disk > space. 4 raidz2s give > more performance, 3 raidz3s gives more reliability. > > -Ross >
Hi Ross, What about old good raid10? It's a pretty reasonable choice for heavy loaded storages, isn't it? I remember when I migrated raidz2 to 8xdrives raid10 the application administrators were just really happy with the new access speed. (we didn't use stripped raidz2 though as you are suggesting). -- Roman -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
