NFSv4 delegation

[Alessio Cecchi]

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(info at 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(info at 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