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From: Thomas Rast <trast@inf•ethz.ch>
To: "Kenneth Ölwing" <kenneth@olwing•se>
Cc: Git List <git@vger•kernel.org>
Subject: Re: Collective wisdom about repos on NFS accessed by concurrent clients (== corruption!?)
Date: Sat, 6 Apr 2013 10:11:33 +0200	[thread overview]
Message-ID: <871uaorscq.fsf@linux-k42r.v.cablecom.net> (raw)
In-Reply-To: <515EE38D.2000502@olwing.se> ("Kenneth \=\?utf-8\?Q\?\=C3\=96lwing\?\= \=\?utf-8\?Q\?\=22's\?\= message of "Fri, 05 Apr 2013 16:45:33 +0200")

Kenneth Ölwing <kenneth@olwing•se> writes:

> On 2013-04-05 15:42, Thomas Rast wrote:
>> 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, thanks for your reply.
>
> I'm assuming I should strace the git commands as they're issued? I'm
> already collecting regular stdout/err output in a log as I go. Is
> there any debugging things I can turn on to make the calls issue
> internal tracing of some sort?

I don't think there's any internal debugging that helps at this point.
Usually errors pointing to corruption are caused by a chain of syscalls
failing in some way, and the final error shows only the last one, so
strace() output is very interesting.

> The main issue I see is that I suspect it will generate so much data
> that it'll overflow my disk ;-).

Well, assuming you have some automated way of detecting when it fails,
you can just overwrite the same strace output file repeatedly; we're
only interested in the last one (or all the last ones if several gits
fail concurrently).

Fiddling with strace will unfortunately change the timings somewhat
(causing a bunch of extra context switches per syscall), but I hope that
you can still get it to reproduce.

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

  reply	other threads:[~2013-04-06 16:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-28 10:22 Collective wisdom about repos on NFS accessed by concurrent clients (== corruption!?) Kenneth Ölwing
2013-04-05 12:35 ` Kenneth Ölwing
2013-04-05 13:42   ` Thomas Rast
2013-04-05 14:45     ` Kenneth Ölwing
2013-04-06  8:11       ` Thomas Rast [this message]
2013-04-06 11:49         ` Jason Pyeron
2013-04-07 18:56           ` Kenneth Ölwing

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