Hi, Just out of curiosity what is in nfsv4 delegation that you think would give a benefit on your configuration?
If I read back the thread you seem to have dovecot configured with director ring in front of the backends. In that case Dovecot already manages storage in a way that only one of the backends is accessing each users data at a time. So I can’t see anything but problems form enabling delegations. Sorry but I have zero experience in running dovegot with nfsv4 delegations since in general it is not needed. Sami > On 18 Aug 2015, at 15:42, Alessio Cecchi <ales...@skye.it> wrote: > > Hi, > > last day I tried to enable "nfsv4 delegation" on my cluster (enable nfsv4.0 > and read delegation on Netapp and remount the volume on Linux Centos 6.7 > clients with Dovecot+Director). > > It was a failure, after some minutes the load on clients was high, and in > dovecot.log I found these errors (repeated continuously): > > Aug 17 20:28:17 pop01eeh dovecot: imap(i...@domain.com): Error: > mail_index_wait_lock_fd() failed with file > /home/domains/domain.com/info/Maildir/dovecot.index.log: Input/output error > Aug 17 20:28:21 pop01eeh dovecot: imap(i...@domain.com): Error: > fcntl(/home/domains/domain.com/info/Maildir/dovecot.index.cache, write-lock, > F_SETLKW) locking failed: Input/output error > > Is really impossible to run NFSv4 with delegation with dovecot? If it were > possible the number of NFS operations would drop so much with many benefits > on performance. > > Il 09/07/2015 17:08, brd ha scritto: >> just a quick update: >> >> no issues with NFSv4.0 (load is slowly growing, currently ~7k mailboxes) >> >> instead, bad news from delegation front, we enabled it for a couple of >> days but we ran in ugly issues: processes went in "uninterruptible >> sleep" state, load average gets huge, reboot was the only escape :-( >> >> -brd >> >> Alessio Cecchi wrote: >>> Il 12/06/2015 13:02, brd ha scritto: >>>> Alessio Cecchi wrote: >>>> [...] >>>>> Have you already try to run NFSv4? >>>> it's in place on a (very) small sample of mailboxes in dbox format, no >>>> issues >>>> up to now (Debian Wheezy mainline kernel) >>> >>> Good to know, let me know what will be when the load will grow. >>> >>>>> When we switch to netapp and nfsv4 we had many problems (lock problems >>>>> and instability) and we had to go immediately to NFSv3. I don't know if >>>>> was a netapp problem or nfs client (Debian with 2.6 kernel), now we are >>>>> using Centos 6 as NFS client and we should re-try to mount mailbox as >>>>> nfsv4. >>>> >>>> when you've had problems, the "delegation feature" was active on Netapp >>>> filers? (AFAIK it is disabled by default) >>> >>> Never enabled "delegation feature" on my netapp. >>> >>> Probably my issue was on client side. I had to switch immediately to NFSv3 >>> without being able to investigate the problem. >>> >>> Ciao >>> -- >>> Alessio Cecchi >>> http://www.linkedin.com/in/alessice > > -- > Alessio Cecchi > http://www.linkedin.com/in/alessice