From: David Greaves <david@dgreaves.com>
To: Guy <bugzilla@watkins-home.com>
Cc: 'Gordon Henderson' <gordon@drogon.net>,
'Philip Molter' <philip@corp.texas.net>,
linux-raid@vger.kernel.org
Subject: Re: Force parity resync on raid5?
Date: Thu, 12 Aug 2004 13:31:12 +0100 [thread overview]
Message-ID: <411B6310.9000406@dgreaves.com> (raw)
In-Reply-To: <200408120406.i7C46s309087@watkins-home.com>
what about
n=0
while
dd if=/dev/md0 of=/tmp/block count=x_for_efficiency seek=n
dd of=/dev/md0 if=/tmp/block count=x_for_efficiency seek=n
n=n+1
loop
?
This would read the good data and force a rewrite - would you need to
stop any optimisers?
David
Guy wrote:
>Ouch! No!!
>
>This would re-build data from parity!!!
>He thinks his parity is bad.
>He wants to re-build the parity from the data!
>I don't know if this can even be done!
>Recovering from a power failure does force a re-build (2.4), but from what I
>remember the system looks like it is re-building a failed disk, which is not
>what he wants to do. If the parity was good, re-building any 1 disk would
>be fine.
>
>Guy
>
>-----Original Message-----
>From: linux-raid-owner@vger.kernel.org
>[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Gordon Henderson
>Sent: Tuesday, August 10, 2004 5:04 AM
>To: Philip Molter
>Cc: linux-raid@vger.kernel.org
>Subject: Re: Force parity resync on raid5?
>
>On Mon, 9 Aug 2004, Philip Molter wrote:
>
>
>
>>How do I force a parity resync on a raid5 array? Under 2.4, I would do
>>this by hard cycling the box and when it came back up, it would
>>automatically resync the array. Under 2.6, this appears to have gone
>>
>>
>away.
>
>I don't know about 2.6, (still living with 2.4) but can't you simply do:
>
> raidhotremove /dev/mdX /dev/hdYZ
>
>followed by
>
> raidhotadd /dev/mdX /dev/hdYZ
>
>or /dev/sdYZ if SCSI disks...
>
>However, picking the right disk to remove might be tricky... And if you
>were at all unsure about data on the disks, maybe rebooting and doing a
>hard fsck of the partition(s) in maintenance mode might be a good thing
>too...
>
>Good luck!
>-
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>-
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>
>
>
next prev parent reply other threads:[~2004-08-12 12:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-09 23:10 Force parity resync on raid5? Philip Molter
2004-08-10 9:04 ` Gordon Henderson
2004-08-12 4:06 ` Guy
2004-08-12 11:52 ` Philip Molter
2004-08-12 12:31 ` David Greaves [this message]
2004-08-12 15:22 ` Guy
2004-08-12 16:26 ` David Greaves
2004-08-12 17:07 ` Philip Molter
-- strict thread matches above, loose matches on Subject: below --
2004-08-10 12:03 Philip Molter
2004-08-10 12:39 ` Neil Brown
2004-08-10 14:30 ` Philip Molter
2004-08-11 2:28 ` Neil Brown
2004-08-11 3:37 ` Philip Molter
2004-08-11 9:23 ` David Greaves
2004-08-12 17:15 Salyzyn, Mark
2004-08-12 18:16 ` Guy
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