RE: Re: Subversion repository on unix mounted dir

Hi David,
  Have you tried executing SVN backups from NFS mounted directory? For
me , the svnadmin hotcopy command fails if I tried executing from NFS
mounted directory showing the "no shared lock found" error..

Since you have your repos on NFS volumes, would like to get your
feedback on this..

Thanks and Regards,
Jaya

-----Original Message-----
From: david.x.grierson_at_jpmorgan.com
[mailto:david.x.grierson_at_jpmorgan.com]
Sent: Thursday, May 08, 2008 2:56 PM
To: Greg Thomas
Cc: users_at_subversion.tigris.org
Subject: Re: Subversion repository on unix mounted dir

Hi Greg,
All of our repositories are held on NFS volumes ... when we migrated our

service from 1.3.2 (with Apache using the prefork MPM) to 1.4.5 (Apache
using the worker [threaded] MPM) we started seeing significant
corruptions
in repositories which were receiving large commits to them.
I couldn't figure out the cause of the issue until I found this thread
in
the svn-dev list:
http://svn.haxx.se/dev/archive-2007-04/0288.shtml
I'm not sure whether this fix has been implemented ... but as soon as we

switched back from the worker MPM to prefork the corruptions stopped
occurring.
My understanding of the issue is that apr-util is used to manage the DAV

activities database which maps DAV ID's to Subversion transactions.
apr-util uses apr_dbm which uses BDB for its internal storage.
The use of BDB on remote filesystems such as NFS will essentially not
work:
http://www.db5.org/ref/env/remote.html
Dg.--
David Grierson
JPMorgan - IB Architecture - Source Code Management Consultant
GDP 228-5574 / DDI +44 141 228 5574 / Email
david.x.grierson_at_jpmorgan.com
Alhambra House 6th floor, 45 Waterloo Street, Glasgow G2 6HS
 

Greg Thomas <thomasgd_at_omc.bt.co.uk>
07/05/2008 09:27

To
users_at_subversion.tigris.org
cc

Subject
Re: Subversion repository on unix mounted dir

On Tue, 6 May 2008 13:47:20 +0100, david.x.grierson_at_jpmorgan.com
wrote:

>Except that FAQ should be updated to stipulate that you should not use
the
>worker MPM within Apache with NFS storage.
>
>The threads won't obey the locks held on files and will (eventually -
>sooner or later depending upon the volume of activity) lead to
repository

>corruption.

I'm showing my ignorance here, but why would svn code in a worker MPM
thread ignore locks when the same code won't normally?

And why is this limited to NFS?

Greg

-- 
This post represents the views of the author and does
not necessarily accurately represent the views of BT.
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