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Posted to users@subversion.apache.org by Tobias Gierke <To...@freenet-ag.de> on 2009/08/18 08:36:58 UTC
Multi-master setup with Apache and NFS feasible ?
Hi,
For performance reasons, we're thinking about setting up two Apache
Servers that both provide access to a shared (FSFS) repository on NFS.
I've found quite a lot of different opinions on such a setup (with
regards to data corruption/locking issues), some are quite old and refer
to SVN <1.5.
Does anybody successfully use this kind of setup (running SVN 1.5.x on
Linux,can't upgrade to 1.6 right now) or should we just get faster
hardware (storage) for our master server and keep the other box as a
hot-standy (using the write-through proxy mechanism) ?
Regards,
Tobias
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Re: Multi-master setup with Apache and NFS feasible ?
Posted by Tobias Gierke <To...@freenet-ag.de>.
Hi,
> On Aug 18, 2009, at 06:22, Tobias Gierke wrote:
>
>>> You can add read-only mirrors if you need more performance. If you
>>> need everyone to be able to write too, then you can set up
>>> write-through proxying on those mirrors.
>>
>> Good point. This would probably be the easier solution (though this
>> whole 'svnadmin dump' stuff using a post-commit hook feels more like a
>> hack, not like a feature).
>
> That would be a hack. :) Perhaps you found outdated documentation.
> Since Subversion 1.4, there is an officially supported way to keep a
> read-only mirror: use the svnsync program. Though ideally you do call
> it from the post-commit (and post-revprop-change) hook(s), since you
> want it to synchronize as soon as any commit (or property change)
> happens.
This was actually taken from the SVN 1.5 documentation
(http://subversion.tigris.org/svn_1.5_releasenotes.html#webdav-proxy). I
probably should've read it more thoroughly though. It says " [...]An
example that does this using |svnadmin dump|/|svnadmin load| and ssh is
provided below. svnsync can probably do the same thing."
So the documentation seems to lack an updated example on how to do this
using svnsync.
>
>
>>> I have been told before that if you use a cluster filesystem like
>>> Apple's Xsan, you can have multiple master servers pointing at the
>>> same repositories and serving them simultaneously, which would help
>>> eliminate your Subversion server as a single point of failure (and
>>> instead make your NAS the single point of failure).
>>>
>>> AFAIK NFS by itself is not a cluster filesystem and thus couldn't be
>>> used in this manner.
>>
>> I can't see why you would need a cluster FS to do this. The main
>> difference between a network FS (NFS,CIFS etc.) and a cluster FS is the
>> fact that a cluster FS doesn't use a central server to manage data
>> access/locking. I think both solutions should work equally well
>> (although performance most likely is quite different).
>
> I don't have experience with these technologies myself, but I did
> participate in prior discussions of the topic on this list, e.g.:
>
> http://svn.haxx.se/users/archive-2007-05/0399.shtml
Thanks for the link , interesting food for thought ;-)
More than 2 years ago, someone
(http://svn.haxx.se/users/archive-2007-05/0381.shtml) stated:
>
> Subversion repositories can exist on NFS shares without problems,
> assuming your NFS implementation has working file locking
>
> However, until 1.5, there are some situations where multiple servers
> accessing the same NFS repository at the same time will cause some
> commits to fail due to the stale file handle issue of NFS.
> When i say multiple servers, i really mean multiple servers. There is
> no problem with a single server accessing an NFS share.
>
> This will not cause repository corruption, but is kind of annoying.
Unfortunately nobody replied to this (maybe a bold statement, given the
amount of people that complain about NFS locking issues) .
Regards,
Tobias
--
Tobias Gierke / Software Entwickler
tobias.gierke@freenet-ag.de
Tel.: +49 (0) 431-90-20566
Fax: +49 (0) 431-90-20570
freenet Cityline GmbH (Ein Unternehmen der freenet AG)
Am Germaniahafen 1-7
D-24143 Kiel
www.freenet.de / www.mobilcom.de / www.freenet.ag
Geschäftsführung: Christoph Vilanek, Stephan Esch, Andreas Jürgensen, Bodo Rebetge, Andreas Sand
Sitz: Kiel, Amtsgericht Kiel HRB 6202 KI
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Re: Multi-master setup with Apache and NFS feasible ?
Posted by Ryan Schmidt <su...@ryandesign.com>.
On Aug 18, 2009, at 06:22, Tobias Gierke wrote:
>> You can add read-only mirrors if you need more performance. If you
>> need everyone to be able to write too, then you can set up
>> write-through proxying on those mirrors.
>
> Good point. This would probably be the easier solution (though this
> whole 'svnadmin dump' stuff using a post-commit hook feels more like a
> hack, not like a feature).
That would be a hack. :) Perhaps you found outdated documentation.
Since Subversion 1.4, there is an officially supported way to keep a
read-only mirror: use the svnsync program. Though ideally you do call
it from the post-commit (and post-revprop-change) hook(s), since you
want it to synchronize as soon as any commit (or property change)
happens.
>> I have been told before that if you use a cluster filesystem like
>> Apple's Xsan, you can have multiple master servers pointing at the
>> same repositories and serving them simultaneously, which would help
>> eliminate your Subversion server as a single point of failure (and
>> instead make your NAS the single point of failure).
>>
>> AFAIK NFS by itself is not a cluster filesystem and thus couldn't be
>> used in this manner.
>
> I can't see why you would need a cluster FS to do this. The main
> difference between a network FS (NFS,CIFS etc.) and a cluster FS is
> the
> fact that a cluster FS doesn't use a central server to manage data
> access/locking. I think both solutions should work equally well
> (although performance most likely is quite different).
I don't have experience with these technologies myself, but I did
participate in prior discussions of the topic on this list, e.g.:
http://svn.haxx.se/users/archive-2007-05/0399.shtml
I don't know if that answers your question.
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Re: Multi-master setup with Apache and NFS feasible ?
Posted by Tobias Gierke <To...@freenet-ag.de>.
Hi,
>
> On Aug 18, 2009, at 03:36, Tobias Gierke wrote:
>
>> For performance reasons, we're thinking about setting up two Apache
>> Servers that both provide access to a shared (FSFS) repository on NFS.
>> I've found quite a lot of different opinions on such a setup (with
>> regards to data corruption/locking issues), some are quite old and refer
>> to SVN <1.5.
>>
>> Does anybody successfully use this kind of setup (running SVN 1.5.x on
>> Linux,can't upgrade to 1.6 right now) or should we just get faster
>> hardware (storage) for our master server and keep the other box as a
>> hot-standy (using the write-through proxy mechanism) ?
>
> AFAIK most projects get by just fine with a single Subversion server.
>
> You can add read-only mirrors if you need more performance. If you
> need everyone to be able to write too, then you can set up
> write-through proxying on those mirrors.
Good point. This would probably be the easier solution (though this
whole 'svnadmin dump' stuff using a post-commit hook feels more like a
hack, not like a feature).
>
> I have been told before that if you use a cluster filesystem like
> Apple's Xsan, you can have multiple master servers pointing at the
> same repositories and serving them simultaneously, which would help
> eliminate your Subversion server as a single point of failure (and
> instead make your NAS the single point of failure).
>
> AFAIK NFS by itself is not a cluster filesystem and thus couldn't be
> used in this manner.
I can't see why you would need a cluster FS to do this. The main
difference between a network FS (NFS,CIFS etc.) and a cluster FS is the
fact that a cluster FS doesn't use a central server to manage data
access/locking. I think both solutions should work equally well
(although performance most likely is quite different).
Thanks for your reply,
Tobias
--
Tobias Gierke / Software Entwickler
tobias.gierke@freenet-ag.de
Tel.: +49 (0) 431-90-20566
Fax: +49 (0) 431-90-20570
freenet Cityline GmbH (Ein Unternehmen der freenet AG)
Am Germaniahafen 1-7
D-24143 Kiel
www.freenet.de / www.mobilcom.de / www.freenet.ag
Geschäftsführung: Christoph Vilanek, Stephan Esch, Andreas Jürgensen, Bodo Rebetge, Andreas Sand
Sitz: Kiel, Amtsgericht Kiel HRB 6202 KI
------------------------------------------------------
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Re: Multi-master setup with Apache and NFS feasible ?
Posted by Ryan Schmidt <su...@ryandesign.com>.
On Aug 18, 2009, at 03:36, Tobias Gierke wrote:
> For performance reasons, we're thinking about setting up two Apache
> Servers that both provide access to a shared (FSFS) repository on NFS.
> I've found quite a lot of different opinions on such a setup (with
> regards to data corruption/locking issues), some are quite old and
> refer
> to SVN <1.5.
>
> Does anybody successfully use this kind of setup (running SVN 1.5.x on
> Linux,can't upgrade to 1.6 right now) or should we just get faster
> hardware (storage) for our master server and keep the other box as a
> hot-standy (using the write-through proxy mechanism) ?
AFAIK most projects get by just fine with a single Subversion server.
You can add read-only mirrors if you need more performance. If you
need everyone to be able to write too, then you can set up write-
through proxying on those mirrors.
I have been told before that if you use a cluster filesystem like
Apple's Xsan, you can have multiple master servers pointing at the
same repositories and serving them simultaneously, which would help
eliminate your Subversion server as a single point of failure (and
instead make your NAS the single point of failure).
AFAIK NFS by itself is not a cluster filesystem and thus couldn't be
used in this manner.
------------------------------------------------------
http://subversion.tigris.org/ds/viewMessage.do?dsForumId=1065&dsMessageId=2384686
To unsubscribe from this discussion, e-mail: [users-unsubscribe@subversion.tigris.org].