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 _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
