Re: Regular ext4 error warning with HD in USB dock

[Ric Wheeler]

On 12/28/2010 05:30 AM, Amir Goldstein wrote:
> On Tue, Dec 28, 2010 at 10:19 AM, Rogier Wolff<R.E.Wolff@xxxxxxxxxxxx>  wrote:
> > On Mon, Dec 27, 2010 at 09:53:43PM -0500, Ted Ts'o wrote:
> > > On Tue, Dec 28, 2010 at 09:53:45AM +1100, Con Kolivas wrote:
> > > > [1048401.773270] EXT4-fs (sde8): mounted filesystem with writeback data mode.
> > > > Opts: (null)
> > > > [1048702.736011] EXT4-fs (sde8): error count: 3
> > > > [1048702.736016] EXT4-fs (sde8): initial error at 1289053677:
> > > > ext4_journal_start_sb:251
> > > > [1048702.736018] EXT4-fs (sde8): last error at 1289080948: ext4_put_super:719
> > > That's actually not an error.  It's a report which is generated every
> > > 24 hours, indicating that there has been 3 errors since the last time
> > > the error count has been cleared, with the first error taking place at
> > > Sat Nov 6 10:27:57 2010 (US/Eastern) in the function
> > > ext4_journal_start_sb(), at line 251, and the most recent error taking
> > > place at Sat Nov 6 18:02:28 2010 (US/Eastern), in the function
> > > ext4_put_super() at line 719.  This is a new feature which was added
> > > in 2.6.36.
> > Nice. But the issue you're not mentioning is: What errors could have
> > happened on the 6th of november? Should Con worry about those errors?
> Ted,
>
> I would like to use this opportunity to remind you about my
> record_journal_errstr()
> implementation, see:
> https://github.com/amir73il/ext4-snapshots/blob/next3-stable/fs/next3/super.c#L157
>
> It records the initial errors messages (which I found to be the most
> interesting),
> in a message buffer on the unused space after the journal super block
> (3K on a 4K block fs).
>
> fsck prints out those messages and clears the buffer.
> In under a year of Next3 fs in beta and production, it has helped me many times
> to analyse bugs post-mortem and find the problem.
>
> If there is demand, I can post the patch for Ext4.
>
> Amir.

I do think that this sounds like a useful addition - should be very useful in 
doing post mortem analysis...

Thanks!

Ric

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