From mboxrd@z Thu Jan  1 00:00:00 1970
From: Roman Mamedov <roman@rm.pp.ru>
Subject: Re: RAID6 and crashes (reporting back re. --bitmap)
Date: Fri, 11 Jun 2010 17:50:46 +0600
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To: John Hendrikx <hjohn@xs4all.nl>
Cc: Neil Brown <neilb@suse.de>, Miles Fidelman <mfidelman@meetinghouse.net>, linux-raid@vger.kernel.org
List-Id: linux-raid.ids

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On Fri, 11 Jun 2010 13:10:23 +0200
John Hendrikx <hjohn@xs4all.nl> wrote:

> > I would be really interested to find out if my assumption of small numb=
ers
> > of bits set is valid.   You can find out the number of bits set at any
> > instant with  "mdadm -X" run on some component of the array.
> >  =20
> I was interested as well, so I ran this command:
>=20
>  > mdadm -X /dev/md2
>=20
> and this is the result(??):
>=20
>         Filename : /dev/md2
>            Magic : d747992c
> mdadm: invalid bitmap magic 0xd747992c, the bitmap file appears to be=20
> corrupted
>          Version : 1132474982
> mdadm: unknown bitmap version 1132474982, either the bitmap file is=20
> corrupted or you need to upgrade your tools

I stumbled in the same way initially, but then re-read more closely and
noticed that Neil said to run it "on some component of the array",
e.g. /dev/sdxN, not the array itself -- and that way it worked fine. Howeve=
r as
my array sees almost no write load at the moment, I have no useful results =
to
report.

--=20
With respect,
Roman

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