Re: git fsck not identifying corrupted packs

From: Wesley J. Landaker <wjl@icecavern.net>
Date: Oct 19, 2009, 19:27 UTC
Message-ID: <200910191327.49092.wjl@icecavern.net>
In-Reply-To: <7v7hur1a0h.fsf@alter.siamese.dyndns.org>

(Not CCing everyone, since this is mostly curiosa in the "using git as it was never intended" section):

On Monday 19 October 2009 13:03:42 Junio C Hamano wrote:

Show 7 quoted lines

> Once a packfile is created and we always use it read-only, there didn't
> seem to be much point in suspecting that the underlying filesystems or
> disks may corrupt them in such a way that is not caught by the SHA-1
> checksum over the entire packfile and per object checksum.  That trust in
> the filesystems might have been a good tradeoff between fsck performance
> and reliability on platforms git was initially developed on and for, but
> it might not be true anymore as we run on more platforms these days.

Filesystems are mostly reliable, but only until your crazy users do strange and terrible things. I have a real, non-toy environment where I use this stack as a [horrible] workaround for some issues beyond my control:

git -> ext4 -> lvm -> dmcrypt -> loop -> sshfs -> cygwin sshd -> SMB share

Amazingly, this works pretty reliably with many gigabytes of data in a git repository, even with the occasional crash because of flakiness with the "sshfs -> cygwin sshd" piece of the puzzle. But a good "git fsck" sure doesn't hurt in this environment! =)