Hard Disk IDs in Linux

Michael Torrie torriem at gmail.com
Tue Mar 12 18:10:21 MDT 2013

On 03/12/2013 01:06 PM, Lonnie Olson wrote:
> Important thing to consider is Murphy's law.  The minimum number of
> disk failures to destroy your whole array.  In RAID6, it's 3 disks.
> In RAID10, it's 2 disks.  Obviously this would have to be a matched
> pair, but s#!* happens.

RAID 6 stores the parity on 2 disks.  So really you can only lose any
two disks in a RAID 6 volume before you have catastrophic data loss.

So laying aside the rebuild times for RAID 6 which can be very long
indeed, if you have a bunch of RAID-6 volumes made up of 4 disks total,
then that's the same redundancy as RAID-10, except that you can lose any
two out of four disks in a RAID-6 volume, whereas with RAID-10, if you
happen to lose two disks that are part of a RAID-1 volume, you are screwed.

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