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From: Dmitriy Kirhlarov (no email)
Date: Mon May 14 2007 - 08:17:36 EDT
On Thu, May 03, 2007 at 05:08:52PM +0200, Paul Dekkers wrote:
> I recently tried to use NFS (on a RedHat client, both to a NetApp filer
> as well as a RedHat NFS server) and I'll share my experiences:
>
> Michael Menge wrote:
> > Cyrus has 2 problems with NFS.
> >
> > 1. Cyrus depends on filesystem locking. NFS-4 should have solved this
> > problem
> > but i have not tested it.
> >
> > 2. BerkleyDB uses shared Memory which does not work accros multiple
> > servers.
>
> I used skiplist in the tests (default with Simon's RPM), and initially
> just used NFSv3 (and I also tested NFSv4): as long as I mounted with the
> -o nolock option it actually worked quite well (also on NFSv3). The
> performance was even better with the NetApp as target than with a local
> filesystem (and NFSv3 was faster than v4).
>
> The nolock options does not disable locking (as I understand it) for the
> filesystem, it just disables locking over NFS, so other nodes won't have
> the same file locked. (Correct me if I'm wrong.) My intention was not to
> have an active-active setup, so in that regard this might not be that
> bad. Not sure what other catches there are though.
Are you try metapartition* options? If you don't need active-active
setup it can be useful.
> I stressed the setup with the imaptest tool from Dovecot, I saw problems
> with that in the past (also with NFSv3 and v4, but in combination with
> Cyrus 2.2 and I'm not sure if I tried nolock), now it seemed to do just
> fine. Only NFSv4 does not seem to be the answer, it seems that -o nolock
> is (on Linux as client).
>
> I'm very hesitant to put this into production, I just wanted to do some
> more tests and ask others after that if they think this is wise or
> not... I couldn't find the time to do more tests... (like see how RedHat
> 5 behaves instead of RedHat 4, if the tric also works on FreeBSD, if I
> can make it fail one way or another... suggestions always welcome...)
On FreeBSD you can use gmirror+ggated for mirroring disk partition
between servers.
WBR.
Dmitriy
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