Re: btrfs csum failed on git .pack file

Markus Trippelsdorf
2009-09-09T07:23:51Z

On Wed, Sep 09, 2009 at 09:01:41AM +0200, Jens Axboe wrote:
> On Wed, Sep 09 2009, Markus Trippelsdorf wrote:
> > On Tue, Sep 08, 2009 at 10:32:14PM +0200, Jens Axboe wrote:
> > > On Tue, Sep 08 2009, Markus Trippelsdorf wrote:
> > > > On Tue, Sep 08, 2009 at 10:00:42PM +0200, Jens Axboe wrote:
> > > > > On Mon, Sep 07 2009, Markus Trippelsdorf wrote:
> > > > > > Just got this error today in my dmesg:
> > > > > > btrfs csum failed ino 1483065 off 158482432 csum 4283543305 private 43905798
> > > > > >
> > > > > > linux % find . -inum 1483065
> > > > > > ./.git/objects/pack/pack-f9251bcc6a8afe3c92193e14d1d742f2f0182ce5.pack
> > > > > >
> > > > > > It's the main pack file from my git linux kernel tree:
> > > > > >
> > > > >
> > > > > Hmm, I ran into something very similar. Care to check what the corrupted
> > > > > block of data looks like (and how big it is)?
> > > >
> > > > I've already deleted the file in question unfortunately.
> > > > On IRC Chris decided that either bad RAM or a harddrive error was the
> > > > most likely reason for this chechsum mismatch.
> > >
> > > Darn, that's too bad. The corruption issue I had was also in a git pack
> > > file. It was fine one day, bad the next. Turned out to be 16kb of 0xff
> > > in the file, and I blamed it on the (cheap) SSD drive that hosted the
> > > local git repo. It's still the most likely explanation given the nature
> > > of the problem, however it would have been really interesting to see
> > > what corruption you had.
> >
> > If by cheap SSD drive you mean an Indilinx Barefoot based one, we might
> > be using the same hardware (30GB Vertex in my case).
>
> Spooky, yes indeed that's the very same drive I'm using. Also see my
> postings on this very issue here, top two entries:
>
> http://axboe.livejournal.com/
>
> So that pretty much looks like it reaffirms some of my suspicions. Is
> the drive in a laptop that you suspend and resume?

No. I use it in my workstation, that I never switch off normally.

> > What a strange coincidence that it affected git pack files in both cases.
> > It's almost too improbable...
>
> Probably more than a coincidence I think, the question is what though...

If it really was an SSD error, then it should happen randomly, messing up
random files. But (contrary to your experience) I never had any issues with
this SSD until this single failed checksum.

--
Markus