How to recovery a corrupted git repo

I have a corrupted git repo, with "git fsck", it shows

missing blob b71eb55f2dbc97dafd4a769fc61f346e69a5e0af missing blob 282035f3ae964e1e288f352c370be8edd11d3078 missing tree 3c20f556eecc476e3542cc522d46a62a4461fec6 missing blob f321b578edeb452358497e832815d6cae6b36886 missing commit 6d23f5084c975be637f7d748db82116bf84d3872

And i also have a good backup repo. How can i recover the corrupted repo with the backup repo?

I can do a rsync or fresh "git clone", however, is there any git related commands to incrementally do this?

btw, "git remote add and then git fetch" doesn't work, it reports

error: refs/heads/bringup does not point to a valid object! error: refs/heads/fsl_imx_r9.3 does not point to a valid object! error: refs/heads/bringup does not point to a valid object! error: refs/heads/fsl_imx_r9.3 does not point to a valid object! error: refs/heads/bringup does not point to a valid object! error: refs/heads/fsl_imx_r9.3 does not point to a valid object! error: refs/heads/bringup does not point to a valid object! error: refs/heads/fsl_imx_r9.3 does not point to a valid object! error: missing object referenced by 'refs/tags/v2.6.32' error: missing object referenced by 'refs/tags/v2.6.32-rc1' error: missing object referenced by 'refs/tags/v2.6.32-rc2'

On Mon, Feb 21, 2011 at 8:50 AM, Ping Yin <pkufranky@gmail.com> wrote:

Please, have a look this FAQ entry:

https://git.wiki.kernel.org/index.php/GitFaq#How_to_fix_a_broken_repository.3F

And tell us what you did according to it.

Thanks, Christian.

Hi, On Mon, Feb 21, 2011 at 03:50:09PM +0800, Ping Yin wrote:

I don't know whether there is a single git command to do it, but you can
copy those 5 objects "by hand": in your backup, you should have a
directory .git/objects, where you have the files
   b7/1eb55f2dbc97dafd4a769fc61f346e69a5e0af
   28/2035f3ae964e1e288f352c370be8edd11d3078
   3c/20f556eecc476e3542cc522d46a62a4461fec6
   f3/21b578edeb452358497e832815d6cae6b36886
   6d/23f5084c975be637f7d748db82116bf84d3872

It should be sufficient to just copy those files into the corrupted repo.

However if you packed the git-files in the backup (e.g. by running "git gc"), those objects might be found in a pack in .git/objects/pack. The easiest ist probably to use git-unpack-objects to unpack the objects, and then copy the 5 missing objects.

Axel

PS: Well, I'm using git and I like it -- but I'm no specialist; so first
do a backup, before you follow my proposal ;-)

Thanks, axel and Christian.

I am just look for a simpler method. since i have a full backup, finally , i do something like following

git clone --bare --reference bad-repo.git foo.com:good-repo.git repo.git

On Mon, Feb 21, 2011 at 6:04 PM, Axel Freyn <axel-freyn@gmx.de> wrote:

Axel Freyn <axel-freyn@gmx.de> writes:

There's also the brute-force approach

rsync $good_repo/.git/objects/ $bad_repo/.git/objects/ cd $bad_repo git gc

Notice the absence of --delete in the rsync command: I'm just adding new files in the $bad_repo, not deleting any (since files with identical names must have identical content).

This will result in a lot of duplicates (objects found in several packs), but "git gc" should be able to remove them.

(the notice about doing backups before also applies to my proposal ;-) )

On Mon, Feb 21, 2011 at 10:51 PM, Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> wrote:

Thanks. This should be an applicable method. However, before rsyncing, the pack should be unpacked first.

Ping Yin <pkufranky@gmail.com> writes:

No need. Just copying the pack files works too, and is way faster:

/tmp/corrupted$ git fsck missing commit 4815c2955d5863005edc4ff61c0de42e9609a920 dangling tree c8b826f673e1f1edb0fb5dc58294148be06cd6cb /tmp/corrupted$ cp ../cloned/.git/objects/pack/pack-e34444a471a9cd3e6f2656b609ffa0d66cce1f9c.* .git/objects/pack/ /tmp/corrupted$ git fsck /tmp/corrupted$ git gc Counting objects: 12, done. Delta compression using up to 2 threads. Compressing objects: 100% (4/4), done. Writing objects: 100% (12/12), done. Total 12 (delta 0), reused 12 (delta 0)

On Mon, Feb 21, 2011 at 11:31 PM, Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> wrote:

Great, thanks.