Re: Strange messages in my kernel log

From: Alexander V. Nikolaev (
Date: Thu Aug 31 2000 - 03:01:50 EST

On Thu, 31 Aug 2000, Neil Brown wrote:

>On Wednesday August 30, wrote:
>> I have strange messages in my kernel log (1-2 messages per day)
>> raid5: bug: stripe->bh_new[2], sector 477640 exists
>> raid5: bh 8ffd6da0, bh_new 8ffd63e0
>> raid5: bug: stripe->bh_new[2], sector 6677320 exists
>> raid5: bh aca1f060, bh_new aca1f720
>> raid5: bug: stripe->bh_new[1], sector 6854048 exists
>> raid5: bh b94c02c0, bh_new b94c0260
>> raid5: bug: stripe->bh_new[2], sector 6889584 exists
>> raid5: bh 833949c0, bh_new 83394d80
>> What does it mean? Can this cause data corruption? Can i fix this problem?
>> I use softvare RAID level 5, in kernel 2.2.16 with RH patches.
>What does it means?
> It means that raid5 received an IO request for a block of data for
> which is already had an outstanding IO request. In these cases the
> two i/o requests had different buffer_head strutures.
> raid5 reports a bug, but actually handles the situation fairly
> gracefully: it blocks the second request until the first has
> finished.
>Can this cause data corruption?
> Not directly, but it might be a symptom of something else that could
> cause corruption.
>Can i fix this problem?
> Maybe, but first we need to understand it.
> The question is, how could there be two different buffer_heads for
> the same block on disk?
> My understanding of the 2.2 buffer cache is not very good, but I
> think that all filesystems and block device IO go through the buffer
> cache, so any of these accesses should never allow two buffer_heads
> to point to the same block.
> However I believe that swapping doesn't go through the buffer cache.
> So: what are you doing with the raid5 partition.
> What sort of file system?
Ext2fs with strige=16

> Are you swapping to a file on the filesystems?
No I have BIG MySQL database on this FS

> Is there any chance that a parity reconstruction is happening when
> you get these messages.
Hmm... Parity reconstuction was complete before i put any data to new
array. I not seen messages about another reconstruction.

> Is there anything at all about your usage of the raid5 device that
> could possibly be at all out of the ordinary?

>> Also I have second question.
>> How much stable software RAID in latset 2.4.0 test series?
>quite stable, but not very fast. RAID5 in 2.4.0 in particular is much
>slower than 2.2.xx with mingo's patches. I'm working on this from
>time to time.
Can I upgrade kernel without rebuild/reformat array?

With best regards 
             Alexander V. Nikolaev
	System administrator of

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