Re: Recover broken git repository?

["Stefan-W. Hahn" <stefan.hahn@s-hahn.de>]

Also sprach Linus Torvalds am Tue, 14 Jul 2009 at 10:33:58 -0700:
> 
> 
> On Tue, 14 Jul 2009, Florian Breitwieser wrote:
> >
> > $ git commit -m "Some message"
> > error: invalid object 1086b1c606a04bcb78b92d1d411a299d20d18034
> > fatal: Error building trees
> 
> Hmm. That "invalid object" error comes from 'update_one()' when it cannot 
> find the object it is looking for. That, in turn, tends to be an issue of 
> the index containing a SHA1 that does not exist in the database.
> 
> Do you trust your filesystem? The symptoms really sound like you did a 
> "git add .." earlier, and populated the index, but now the object that got 
> populated is no longer found.
> 
> What OS, what filesystem?  Oh, and what version of git?
> 
> > $ git-fsck --full
> > dangling tree c2549a3cdd83098a523cb707f217f4656cde7eb5
> 
> The fsck seems to imply that things are ok. The fsck _should_ have checked 
> the index too.
> 
> The 'git commit' obviously disagrees.
> 
> Two things to check:
> 
>  - do you use grafts to hide old history, rather than connect additional 
>    history?
> 
>    That can be really dangerous, and will make fsck (and other tools) not 
>    look at the hidden state. 
> 
>  - do you have alternates (is multiple _different_ repositories tat point 
>    to each other)? That can cause problems if you then do things like git 
>    prune in them. It wouldn't explain this particular case, but it's 
>    something I look out for when I hear about corruption.
> 
> > $ git prune
> 
> Not a good idea. When you suspect corruption, the _last_ thing you want to 
> do is prune things. Who knows what happened?
> 
> > $ git commit -m "Some message"
> > Created commit e32d5dd: Some message
> >  2 files changed, 167 insertions(+), 10 deletions(-)
> 
> So now the same commit worked? It _really_ sounds like your filesystem has 
> a hard time finding the files it just created. Some local caching issue.
> 
> Is it a network filesystem? If so, what's the filesystem server and 
> version, if you can find it out?
> 
> > $ git push
> > Counting objects: 15, done.
> > Compressing objects: 100% (6/6), done.
> > Writing objects: 100% (8/8), 2.44 KiB, done.
> > Total 8 (delta 4), reused 0 (delta 0)
> > Unpacking objects: 100% (8/8), done.
> > fatal: unresolved deltas left after unpacking
> > error: unpack failed: unpacker exited with error code
> > To /mnt/extstore2/bioinformatic/git/ppi.git
> >  ! [remote rejected] master -> master (n/a (unpacker error))
> > error: failed to push some refs to
> > '/mnt/extstore2/bioinformatic/git/ppi.git'
> 
> Here the other end doesn't have some object that we expect it to have, and 
> that we sent a delta to it against. Sounds like potentially the exact same 
> problem (it created some new file, but then couldn't see it). Is the thign 
> you are pushing to a similar machine with similar filesystems?
> 
> We've had issues with both CIFS and NFS. Using
> 
> 	[core]
> 		fsyncobjectfiles = true
> 
> might work around some issues where the filesystem does crazy things. But 
> I'd really like to hear what OS and filesystem versions you're running.
> 
> 			Linus
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-- 
Stefan-W. Hahn                          It is easy to make things.
/ mailto:stefan.hahn@s-hahn.de /        It is hard to make things simple.			

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