[ILUG] ext3 strangeness on software raid

[John Allen]

On Saturday 27 March 2004 00:46, Niall O Broin wrote:
> I have a box using kernel software RAID-1 on two SCSI disks. There are two
> RAIDs, mdo consisting of sda5 and sdb5 and md1, consisting of sda6 and
> sdb6. There is an ext3 FS on each of md0 and md1. Lately I have experienced
> some filesystem corruption on md0 which puzzles me, and cause me no small
> concern. I'm not yet in a position to boot the box from a rescue CD but in
> the absence of that I have been having a look around and I saw this in
> /var/log/messages
>
>
> Mar 26 12:53:13 rh9box kernel: EXT3 FS 2.4-0.9.19, 19 August 2002 on
> sd(8,5), internal journal
> Mar 26 12:53:13 rh9box kernel: Adding Swap: 2152700k swap-space (priority
> -1) Mar 26 12:53:13 rh9box kernel: kjournald starting.  Commit interval 5
> seconds Mar 26 12:53:13 rh9box kernel: EXT3 FS 2.4-0.9.19, 19 August 2002
> on md(9,1), internal journal
> Mar 26 12:53:13 rh9box kernel: EXT3-fs: mounted filesystem with ordered
> data mode.
> Mar 26 12:53:13 rh9box kernel: EXT3-fs error (device sd(8,5)):
> ext3_free_blocks: bit already cleared for block 17
> 04643
>
> and a few seconds later, more errors.
>
> Mar 26 12:53:40 rh9box kernel: EXT3-fs error (device sd(8,5)):
> ext3_free_blocks: bit already cleared for block 3999498
> Mar 26 12:53:40 rh9box kernel: EXT3-fs error (device sd(8,5)):
> ext3_free_blocks: bit already cleared for block 3999502
> Mar 26 12:53:40 rh9box kernel: EXT3-fs error (device sd(8,5)):
> ext3_free_blocks: bit already cleared for block 3999499
> Mar 26 12:53:40 rh9box kernel: EXT3-fs error (device sd(8,5)):
> ext3_free_blocks: bit already cleared for block 3999500
>
>

I'm getting the same on my RAID-1 partitions (ReiserFS), ie. mad device names 
rather than the actual devices that make up the mdX.

> What's puzzling me here is the reference to EXT3-fs error (device sd(8,5)) 
> as there isn't an EXT3-fs on sd(8,5) (sda5) but rather on md0. Now I know
> that the way Linux RAID1 is made, you can effectively see the filesystem on
> either of the components of the RAID, but how is the kernel seeing this?
> There is never an attempt to access that partition on its own but only as a
> component of the RAID. There's no reference in /var/log/messages to sdb5 or
> sd[ab]6. I see no equivalents to
>
>
> Mar 26 12:53:13 rh9box kernel: EXT3 FS 2.4-0.9.19, 19 August 2002 on
> sd(8,5), internal journal
>
> for any other sd  partition.   Any ideas?
>
>
> --
> Niall

-- 
John Allen,                          mailto:john.allen at dublinux.net
MandrakeClub Silver Member.          http://www.dublinux.net

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