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From: Stan Hoeppner <stan@hardwarefreak.com>
To: NeilBrown <neilb@suse.de>
Cc: Ivan Lezhnjov IV <ivan.lezhnjov.iv@gmail.com>,
	"linux-raid@vger.kernel.org" <linux-raid@vger.kernel.org>
Subject: Re: Running check and e2fsck simultaneously
Date: Sun, 10 Nov 2013 16:36:35 -0600	[thread overview]
Message-ID: <52800A73.9020401@hardwarefreak.com> (raw)
In-Reply-To: <20131111073428.583b83b2@notabene.brown>

On 11/10/2013 2:34 PM, NeilBrown wrote:
> On Sun, 10 Nov 2013 13:17:21 -0600 Stan Hoeppner <stan@hardwarefreak.com>
> wrote:
> 
>> Also, I see little/no value in running a scheduled mdadm check on a
>> RAID1 array.  Any problems with RAID1 will be due to one of the disks
>> beginning to fail in some mode, usually requiring sector relocation.
> 
> I think scrubbing has value on any RAID with redundancy.

That's a bit... redundant, Neil. :)

> The firmware can only relocate a sector if it reads it when it is marginal
> but not yet completely lost.  If a sector is not read for a long time and
> during that time the media degraded beyond recovery the firmware cannot do
> anything.  But RAID1 can - it can get it from the other device.

But is a scrub required for this?  Isn't this exactly what occurs during
normal operation with md/RAID1?  I.e. a read fails with disk error, so
we grab the sector from the mirror?  So what advantage is there to
scrubbing md/RAID1?

-- 
Stan

  reply	other threads:[~2013-11-10 22:36 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-10 16:06 Running check and e2fsck simultaneously Ivan Lezhnjov IV
2013-11-10 18:08 ` Stan Hoeppner
2013-11-10 18:12   ` Ivan Lezhnjov IV
2013-11-10 19:17     ` Stan Hoeppner
2013-11-10 19:35       ` Ivan Lezhnjov IV
2013-11-10 20:12         ` Stan Hoeppner
2013-11-10 23:08           ` Ivan Lezhnjov IV
2013-11-11  3:43             ` Stan Hoeppner
2013-11-11  7:52               ` Ivan Lezhnjov IV
2013-11-11  8:09                 ` David Brown
2013-11-11  8:29                   ` Ivan Lezhnjov IV
2013-11-10 20:34       ` NeilBrown
2013-11-10 22:36         ` Stan Hoeppner [this message]
2013-11-10 22:51           ` NeilBrown
2013-11-10 22:54           ` Adam Goryachev
2013-11-11  2:08             ` Stan Hoeppner
2013-11-10 23:11         ` Ivan Lezhnjov IV

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