From: Neil Brown <neilb@cse.unsw.edu.au>
To: Kirill Malkin <malkin@reldata.com>
Cc: "'linux-raid@vger.kernel.org'" <linux-raid@vger.kernel.org>
Subject: Re: changing major/minor numbers
Date: Mon, 20 May 2002 21:27:53 +1000 (EST) [thread overview]
Message-ID: <15592.56761.586254.465550@notabene.cse.unsw.edu.au> (raw)
In-Reply-To: message from Kirill Malkin on Thursday May 16
On Thursday May 16, malkin@reldata.com wrote:
> Hi,
>
> I have a basic question about Linux RAID implementation: how to recover or
> restart a RAID set when the individual disks are moved to a different SCSI
> ID, i.e. when their minor (or major or both) number(s) change?
>
> I've experimented with a RAID-1 configuration and found that whenever I move
> one of the disks to a different SCSI ID, the set must be recovered manually
> (i.e. raidhotadd) and the kernel initiates a full copy, even if raidtab is
> manually updated (I guess the system simply looks at the superblocks as the
> first choice). Is it possible to restart the set automatically or at least
> avoid the full copy?
>
> Another question: is there a utility that could identify RAID sets before
> they are started, such as display the superblock contents and verify whether
> any devices are missing or have been moved? There seems to be a considerable
> amount of code, both in kernel and in raidtools, that prints out the content
> of the superblocks, but only if there is a problem or debug mode is
> on.
Get mdadm.
http://www.cse.unsw.edu.au/~neilb/source/mdadm/
(1.0.0 is recommended, 1.0.1 is experimental).
It should answer all your questions.
NeilBrown
>
> The main reason behind these questions is the emergence of iSCSI devices
> that could be connected in a random order thus breaking RAID functionality.
> It would be nice to identify such devices up-front, make necessary
> configuration changes and restart complete RAID sets without the full copy,
> even if the disks come up as different major/minor numbers. Please let me
> know if there's been any thinking in this direction.
>
> Thank you in advance,
> Kirill
>
>
> -
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prev parent reply other threads:[~2002-05-20 11:27 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-05-16 23:34 changing major/minor numbers Kirill Malkin
2002-05-20 11:27 ` Neil Brown [this message]
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