The Care and Feeding of Git
Git requires a bit of tender loving care from time to time. It may seem a bit odd, but occasionally you should run a few commands on your repositories to make sure they're healthy and running as quickly as possible.
garbage collection
The git gc command is an important one to remember.
It will pack up your objects into the delta-compressed format,
saving you a lot of space and seriously speeding up several commands.
$ git gc
Generating pack...
Done counting 91 objects.
Deltifying 91 objects...
100% (91/91) done
Writing 91 objects...
100% (91/91) done
Total 91 (delta 33), reused 0 (delta 0)
Pack pack-9ca918b18abca509b2de71439522a62178415ebd created.
Removing unused objects 100%...
Done.
If can turn gc'ing automatically on and off by setting a configuration setting to '1' or '0':
git config --global gc.auto 1
This will make git automatically gc itself occasionally. You may want to setup a cron to do this at night, however, as it can take a while sometimes on really large repositories.
fsck and prune
If you want to check the health of your repository, you can run 'git-fsck', which will tell you if you have any unreachable or corrupted objects in your database and help you fix them.
$ git fsck
dangling tree 8276318347b8e971733ca5fab77c8f5018c75261
dangling blob 2302a5a4baec369fb631bb89cfe287cc002dc049
dangling blob cb54512d0a989dcfb2d78a7f3c8909f76ad2326a
dangling tree 8e1088e1cc1bc67e0ef01e018707dcb07a2a562b
dangling blob 5e069ed35afae29015b6622fe715c0aee10112ad
Which you can then remove with 'git-prune' (you can run it with '-n' first to see what it will do)
$ git prune -n
2302a5a4baec369fb631bb89cfe287cc002dc049 blob
5e069ed35afae29015b6622fe715c0aee10112ad blob
8276318347b8e971733ca5fab77c8f5018c75261 tree
8e1088e1cc1bc67e0ef01e018707dcb07a2a562b tree
cb54512d0a989dcfb2d78a7f3c8909f76ad2326a blob
$ git prune
$ git fsck