[Gluster-users] 2.0.3

Vikas Gorur vikas at gluster.com
Tue Jul 14 03:48:11 PDT 2009


----- "Stephan von Krawczynski" <skraw at ithnet.com> wrote:

> Maybe I should more precisely explain what I am doing, in case there
> are related problems.
> 
> I am using a copy of the opensuse 11.1 DVD for that test. I copy the
> whole DVD files into a directory called "suse" on the first server. The
> directory "suse" is located on the top level of the gluster-exported "/p3". Then I
> start "ls -lR" on one of two connected clients and watch it flow. In the
> meantime you can see the directories and files being created on the second server.

> After some minutes the "ls" exits correctly. Then looking at the second
> servers' "suse" directory reveals it has incorrect mtime at least on the "suse"
> dir. My personal opinion is that this derives from the files being added
> _inside_ the directory during the healing process. Nevertheless glusterfs should
> handle that case like rsync does, too.

> Another thing you can see in this example: if you repeat "ls -lR" you
> will notice quite some directories inside the healed "suse" tree have wrong
> mtime (from the healing) displayed during ls. This proves that mtime
> displayed on the client does not always come from the first server. And it proves
> that this really is a production no-go, because your mtimes are indeed flapping
> after this healing process.

Ah, finally! Thanks for the detailed explanation. I wasn't reproducing the problem
because I just tried it with empty directories, and not with directories which contained
files inside them.

The problem in a nutshell is this:

Whenever replicate self-heal creates an entry (file or directory), it does not sync
the parent directory's mtime. The fix is to sync it after every create.

However, we've chosen to defer the fix, since there are some changes planned
for 2.1 that will make it very easy to fix this (it is planned for all create
operations to return stat info for the parent directory). Fixing it now on the other hand
will involve significant work.

You can track the progress of this issue at:
http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=137
Vikas



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