Hi, 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. 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...) Paul P.S. For us it would be interesting to use this. I can still keep replication as fallback too, but other than that I can have faster failover to another primary server with NFS and something like heartbeat... and I think a lot of overhead is right now in the ext3 fs. (And the server would be a NetApp with WAFL, probably more efficient.) ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
