Re: btrfs csum failed on git .pack file

Jens Axboe
2009-09-09T08:26:36Z

On Wed, Sep 09 2009, Daniel J Blueman wrote:
> On Wed, Sep 9, 2009 at 8:01 AM, Jens Axboe<jens.axboe@oracle.com> 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?
>
> If you're on firmware < 1.30, the changlog includes some fixes which
> may be relevant, eg if "block 0" is relative, or you're
> suspending/resuming:
>
> - Race condition occurred during soft reset handler
> - If read fail occurs during reading stamp information, firmware
> corrupted block 0.
> - Power off recovery had bug in certain circumstances
>
> http://www.ocztechnologyforum.com/forum/showthread.php?t=57516

The issue is pretty much moot at this point, since OCZ support were not
really interested in providing any sort of real technical support to
find out what really caused this issue. My main worry was reliability of
these cheaper SSD drives, and that worry is still not resolved. If you
read the blog entries, I do comment on the apparently scary basic bugs
taht are still being fixed on the Indilinx controllers. I do expect some
basic level of data integrity from a consumer product and at least some
interest in resolving weird corruption issues if things go wrong. Since
OCZ cannot provide anything like that, I have a hard time recommending
these drives for anything but very casual use. Fast, cheap, reliable.
Pick any two.

My drive was running 1.10 at the time of the problem.

--
Jens Axboe