[plug] RAID, and what it can't solve

Craig Ringer craig at postnewspapers.com.au
Tue Jun 22 07:08:05 WST 2004


Hi folks

I thought I'd drop a note to remind anyone considering RAID that it's
not total data protection. Backups, backups, backups.

Why do I mention this now? Because I just had my own paranoia borne out
by a double disk failure in a 4 disk RAID 5 array. Darn thing was half
way through rebuilding onto the hot spare when the second disk died. The
array is only two days old, too - 4x250GB SATA Western Digital disks, +
hot spare.

Thankfully, I keep system snapshots on SATA disks (mmm... hot swap) in
addition to tape backups, and of course I'd just updated the snapshot
when migrating from the old array. I was able to make a fresh snapshot
off the degraded array before trying to rebuild - just in case something
might've been misssed - so didn't lose even a tiny bit of data.

--
Craig Ringer




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