RE: NFS and performances

2023-02-15 Thread Marc 
> 
> I apologize in advance as you probably don't want to here this.

:) apology accepted!

> I have a replicated system and tried to use NFS to a file share server
> with dedicated gigabit links etc and my second replicated system.
> 
> I have 300+ accounts and many have 20+ gig of data over 600+ folders,
> your setup seems larger.
> 
> I spent 2 months trying to make this work reliably with nothing working
> out.
> 
> that being said (and this IS NOT a dovecot thing) NFS simply will not
> work reliably especially in the environment that you seem to be using
> 
> I went to local SDRAM drives on the second server and have had zero
> issues since.

Even a bit bigger setup would run ok on ceph. I have more or less default setup 
but have split up mailboxes on ssd and hdd, indexes on ssd. Although it is much 
slower than native performance. You have complete redundancy.

Re: NFS and performances

2023-02-15 Thread Paul Kudla (SCOM.CA Internet Services Inc.) 



Good morning

I apologize in advance as you probably don't want to here this.

I have a replicated system and tried to use NFS to a file share server 
with dedicated gigabit links etc and my second replicated system.


I have 300+ accounts and many have 20+ gig of data over 600+ folders, 
your setup seems larger.


I spent 2 months trying to make this work reliably with nothing working out.

that being said (and this IS NOT a dovecot thing) NFS simply will not 
work reliably especially in the environment that you seem to be using


I went to local SDRAM drives on the second server and have had zero 
issues since.


NFS tweaks can be done and dovecot does try to support this but Linux 
flavors (i use FreeBSD) all seem to handle NFS slightly differently thus 
leading to the issues of timeouts, data not so much being dropped but 
delayed between the NFS mount points.


NFS inherently on most systems runs a 30 second cache and file locking 
for the mailboxes can usually is an issue.


Just easier to use hdd's on any local server.

NFS is good for tar backups etc though.

Happy Wednesday !!!
Thanks - paul

Paul Kudla


Scom.ca Internet Services 
004-1009 Byron Street South
Whitby, Ontario - Canada
L1N 4S3

Toronto 416.642.7266
Main 1.866.411.7266
Fax 1.888.892.7266
Email p...@scom.ca

On 2023-02-15 9:25 a.m., tomate aceite wrote:

Hello,  i have some question about NFS, dovecot director, and imap settings.

I was reading all dovecot documentation ad mail lists, but some aspect  
are not clear to me.


I am looking for performance / tunning my infra to work in a more 
efficient way because we experiences some issues some days ago.


This is my infra:

I got an infra with 2 dovecot-directors and 3 imap backend.
I got all the emails stored in a common NFS share filer to all the imap 
nodes. ( Index are locally stored in each imap node.)



My NFS mount options:

(0)#: nfsstat -m

/data/mail from myipaddress:/export/mail/maildirs
  Flags:

rw,nosuid,noexec,noatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,nordirplus,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=10.0.0.205,mountvers=3,mountport=20048,mountproto=tcp,local_lock=none,addr=10.0.0.205



*Questions*:  ( https://wiki.dovecot.org/PerformanceTuning 
 , 
https://doc.dovecot.org/configuration_manual/nfs/ 
  >> i am following 
these steps )


1) Is my NFS correct setup with the mount options well optimized ?  Not 
sure if someone is using the same flags that me or got a better 
recomendation to used.


2) Set *mmap_disable = yes ??? * >>  This must be set to yes if you 
store indexes to shared filesystems. In my case i got them locally in 
each imap node not in NFS share folder.


I got setup  mmap_disable = no , is this correct?  I think no is the 
correct option here with indexes locally.


because i can read here:

https://wiki1.dovecot.org/NFS 


 >> High performance NFS setup with indexes on local disk (see below
for benefits):

mmap_disable = no



3) Set*mail_fsync = always  ???*

Documentation: https://wiki.dovecot.org/PerformanceTuning 



always

     Use fsync after all disk writes.

     Recommended for NFS to make sure there aren’t any delayed write()s.


3.a) where i can setup this option *mail_fsync = always , *because i 
run  doveconf -n in director,  and imap nodes, and they are not showing 
nothing.


3.b) *In which node ? *Do i need to add  the setting in dovecot.conf in 
*director node or in imap node or in both ?*  Not sure if this is the 
correct way:


This is an attemp of setup, not sure if is correct?

0)#: doveconf -n
# 2.3.13 (89f716dc2): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.13 (cdd19fe3)
# OS: Linux 5.10.0-20-amd64 x86_64 Debian 11.6

mail_debug = yes
mail_fsync = always
mail_max_userip_connections = 20
mail_nfs_storage = yes
mail_plugins = " notify mail_log"
mail_privileged_group = mail



protocol lmtp {
   mail_fsync = always
   mail_plugins = " notify mail_log sieve mail_lua push_notification
push_notification_lua"
   plugin {
    ...
   }



4) Do not set *mail_nfs_index *or *mail_nfs_storage* (i.e. keep them as 
no)   ?


First option make sense but the second one not.

https://doc.dovecot.org/settings/core/#core_setting-mail_nfs_storage 



mail_nfs_storage

         Default: no

         Values: Boolean

     Flush NFS caches whenever it is necessary to do so.


     This setting should only be enabled if you are using multiple
servers on NFS.


So should be possible to enable this option *mail_nfs_storage = yes ?*




4) I got this setting in *dovecot-sql.conf  ( director ) *