Subject: Re: Collective wisdom about repos on NFS accessed by concurrent clients (== corruption!?)

From: Thomas Rast <[email-masked]>
Date: Fri, 5 Apr 2013 15:42:04 +0200

Kenneth Ölwing <[email-masked]> writes:

> Basically, I'm at a place where I'm considering giving up getting this
> to work reliably. In general, my setup work really fine, except for
> the itty-bitty detail that when I put pressure on things I tend to get
> into various kinds of trouble with the central repo being corrupted.
>
> Can anyone authoritatively state anything either way?

My non-authoritative impression was that it's supposed to work
concurrently.  Obviously something breaks:

>> My experience so far is that I eventually get repo corruption when I
>> stress it with concurrent read/write access from multiple hosts
>> (beyond any sort of likely levels, but still). Maybe I'm doing
>> something wrong, missing a configuration setting somewhere, put an
>> unfair stress on the system, there's a bona fide bug - or, given the
>> inherent difficulty in achieving perfect coherency between machines
>> on what's visible on the mount, it's just impossible (?) to truly
>> get it working under all situations.

Can you run the same tests under strace or similar, and gather the
relevant outputs?  Otherwise it's probably very hard to say what is
going wrong.

In particular we've had some reports on lustre that boiled down to
"impossible" returns from libc functions, not git issues.  It's hard to
say without some evidence.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch