[Dovecot] nfs, dovecot, and maildirs
Hello - I know I am not the only one that will be trying, or has tried this before. Here are my questions!
NFS Clients, multiple servers running dovecot - linux with 2.6 kernel with relevant patches (utime, etc) Backend - netapp filer End users - various clients all running IMAP
It looks like 1.0.beta8 is definately the way to go. I have a few questions with regards to setup.
Is it now possible to reliably store index files over nfs?
If not, the alternative is keeping index files in memory, or on local disk - on each server. How big of a performance hit is this if imap connections are round-robined between imap servers?
I've seen various people using different actimeo settings, some set at 0, some slightly higher - as much as 30. Can anyone speak on experience they have had with netapps on this subject?
The following sound like they are required:
mmap_disable=yes lock_method=dotlock
Has anyone been successful with fnctl() on netapps with dovecot?
Thanks in advance!
Hi,
We're currently running a similar setup to what you describe:
Dovecot-1.0.alpha4
Maildir
Netapp/NFS exported mailstore (also home to the dovecot indices)
mmap_disable=yes
lock_method=fnctl
default actimeo (which correspond to the higher end of what you've observed)
Indices seem happy enough being served up from NFS. That is, there's been no observable side-effects.
I would be very interested in hearing how you get on with multiple dovecot instances accessing the underlying mailstore/index files as this is a direction in which we're considering.
Regards,
John.
From: dovecot-bounces@dovecot.org [mailto:dovecot-bounces@dovecot.org] On Behalf Of bofh list Sent: Wednesday, 14 June 2006 3:26 a.m. To: dovecot@dovecot.org Subject: [Dovecot] nfs, dovecot, and maildirs
Hello - I know I am not the only one that will be trying, or has tried this before. Here are my questions!
NFS Clients, multiple servers running dovecot - linux with 2.6 kernel with relevant patches (utime, etc) Backend - netapp filer End users - various clients all running IMAP
It looks like 1.0.beta8 is definately the way to go. I have a few questions with regards to setup.
Is it now possible to reliably store index files over nfs?
If not, the alternative is keeping index files in memory, or on local disk - on each server. How big of a performance hit is this if imap connections are round-robined between imap servers?
I've seen various people using different actimeo settings, some set at 0, some slightly higher - as much as 30. Can anyone speak on experience they have had with netapps on this subject?
The following sound like they are required:
mmap_disable=yes lock_method=dotlock
Has anyone been successful with fnctl() on netapps with dovecot?
Thanks in advance!
On Tue, 2006-06-13 at 11:25 -0400, bofh list wrote:
Is it now possible to reliably store index files over nfs?
It was entirely reliable with me with actimeo=0. You already did look at the NFS wiki page, right? http://wiki.dovecot.org/NFS
If not, the alternative is keeping index files in memory, or on local disk - on each server. How big of a performance hit is this if imap connections are round-robined between imap servers?
I'd say it's a big since you practically can't make any use of the indexes, which are the thing that makes Dovecot so much faster than others.
Even ignoring the indexes the user-round-robining can be a performance hit because the servers can't keep the mail data cached and they always need to fetch everything from NFS server.
I guess this isn't so big of a problem as long as the clients use longliving connections, but with eg. webmails if each connection went to different server that could be really bad.
I've seen various people using different actimeo settings, some set at 0, some slightly higher - as much as 30. Can anyone speak on experience they have had with netapps on this subject?
If a user accesses mails using different servers within the actimeo time, things can break. So larger values can give better performance, but they also increase the risk of using stale cached values which break things.
The following sound like they are required:
mmap_disable=yes lock_method=dotlock
Has anyone been successful with fnctl() on netapps with dovecot?
fcntl locking worked fine with my tests.
participants (3)
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bofh list
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John Newman
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Timo Sirainen