bin/166589: atacontrol(8) incorrectly treats RAID10 and 0+1 the same
Alexander Motin
mav at FreeBSD.org
Tue Jan 15 08:20:01 UTC 2013
The following reply was made to PR bin/166589; it has been noted by GNATS.
From: Alexander Motin <mav at FreeBSD.org>
To: Allen Landsidel <landsidel.allen at gmail.com>
Cc: bug-followup at FreeBSD.org
Subject: Re: bin/166589: atacontrol(8) incorrectly treats RAID10 and 0+1 the
same
Date: Tue, 15 Jan 2013 10:12:14 +0200
That is clear and I had guess you mean it, but why do you insist that
such RAID0+1 variant should even exist if it has no benefits over
RAID10, and why it should be explicitly available to user?
On 15.01.2013 04:51, Allen Landsidel wrote:
> They are not variants in terminology, they are different raid levels.
> Raid0+1 is two RAID-0 arrays, mirrored into a RAID-1. if one of the
> disks fails, that entire RAID-0 is offline and must be rebuilt, and all
> redundancy is lost. A RAID-10 is composed of N raid-1 disks combined
> into a RAID-0. If one disk fails, only that particular RAID-1 is
> degraded, and the redundancy of the others is maintained.
>
> 0+1 cannot survive two failed disks no matter how many are in the
> array. 10 can survive half the disks failing, if it's the right half.
>
> This is something people who've never used more than 4 disks fail to
> grasp, but those of us with 6 (or many many more) know very well.
>
> On 1/14/2013 21:46, Alexander Motin wrote:
>> There could be variants in terminology, but in fact for most of users
>> they are the same. If you have opinion why they should be treated
>> differently, please explain it.
--
Alexander Motin
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