Multiple servers and NFS

Thu Jul 24 20:09:33 UTC 2014

Hello Eduardo,

Thank for your reply.

2 days ago I've try to setup the "INDEX" and "CONTROL" file on my local Harddrive (outside the NFS who the maildir it's stored).

That was my config line:
maildir:%h:INDEX=/opt/dovecot/indexes/%u:CONTROL=/opt/dovecot/indexes/%u

But that was allway slow on the first access, I've think the "cache" expire after 1h for example and Dovecot need make a new "cache" after and that's the reason why the first access need 60 sec. and the next access need just 10 sec.

I've read the dovecot doku, she's really more clear that postfix doku... really :)
It's easy to read it and understand the doc because we learn step by step and when we're in one step we learn everything about it and don't need to go in another section and come back again for finish the step...

Now I think my config (NFS mount/options) it's just a little poor and that's the reason why it's slow.

Bests Regards,
Nathan

----- Mail original -----
De: "Eduardo Ramos" <eduardo at freedominterface.org>
À: dovecot at dovecot.org
Envoyé: Jeudi 24 Juillet 2014 19:27:50
Objet: Re: Multiple servers and NFS

Hi Nathan!

I think you can consider about your index files. By default dovecot 
stores index files in mailbox, but you can define another location. 
Local disk could be better choice. Take I look at this:

http://wiki2.dovecot.org/MailLocation
http://wiki2.dovecot.org/MailLocation/SharedDisk
http://wiki2.dovecot.org/IndexFiles

I think it will help you.

On 07/24/2014 02:09 PM, Nathan Schultheiss wrote:
> Hi Eduardo,
>
> Since I few day I try to setup this config 2, but I've really problem with the NFS.
>
> We come from Google Apps :) I several people on the hospital have large mailbox.
> For example 96000 mails in the INBOX folder, when I do "ls" that is quick for display mail, but with dovecot... I need wait 1 minuts the first time and after display the amount of mail it's quick.
>
> We don't have NetAPP, we've Dell Equallogic with SATA2 7200rpm, gigabits ports.
> The Equallogic it's just for store email, and index file.
>
> My config:
>
> Dell Equallogic
> |-> VMWare ESXI (iscsi mount in VMware with VMWare VMFS 5 format 4To)
> |--> Mounted as slave disk on a VM Ubuntu and exported with this options "(rw,no_subtree_check,all_squash,anonuid=1000,anongid=1000,async)" and formated as ReiserFS (I've read it's the best for many small files).
> |---> My 2 Dovecot Backend mount the NFS (fstab) to my previous VM with this options "nfs  defaults  0  0"
> |----> Mail it's stored in MailDir format "mail_location = maildir:%h"
>
> When I go on Roundcube with a mailbox who I've 96000 in the INBOX "cur" folder, the first time I need 1 minutes waiting.
> The second time it's a little more quick 10 seconds... But when I go back again (after a few hours) it's slow again... And we'are just 5 users at the moment for test...
>
> I've not setup director for the moment I try first dovecot on my lab befor add director and move mailbox from Google...
>
> Have you recommandation for tune or make NFS more quickly, because with Google it's really fast (ok it's google) but if we move to a more slow system, the user on the hospital would no be happy.
> I've try many config, but no really success for have a fast NFS, I don't know if the problem it's VMWARE or if the problem it's just my NFS options.
>
> I'm not pettry good with linux, I'm most good with Windows server, I'm not a good man Google, Microsoft, I know it's devil for every linux sysadmin :)
>
> Thanks,
> Nathan
>
> ----- Mail original -----
> De: "Eduardo Ramos" <eduardo at freedominterface.org>
> À: dovecot at dovecot.org
> Envoyé: Jeudi 24 Juillet 2014 14:01:33
> Objet: Re: Multiple servers and NFS
>
> Hi Richard,
>
> You can use one or more instances of Dovecot on the same machine, as you
> can see here (http://wiki2.dovecot.org/RunningDovecot) "Running Multiple
> Invocations of Dovecot".
>
> The problem with DNS round-robind is that if you server goes down, DNS
> continues resolving for it. I would recommend use some balancer like
> LVS+keepalived.
>
> Consider that multi layer solution:
> --------------------            --------------------
> | LVS + keepalived |            | LVS + keepalived |
> --------------------            --------------------
>            |                                |
>     --------------                   --------------
>     | Director 1 |                   | Director 2 |
>     --------------                   --------------
>            |                                |
>    -----------------               -----------------
>    | IMAP/POP/LMTP |               | IMAP/POP/LMTP |
>    |    Backend    |               |    Backend    |
>    -----------------               -----------------
>            \                                /
>             \                              /
>              \       ------------         /
>               -------|  NetAPP  |---------
>                      ------------
>
> Remember, directors and backends could run on the same machine. I have a
> lab running that way. Maybe I can help you deploy.
> On 07/23/2014 07:23 PM, Richard Hector wrote:
>> Hi all,
>>
>> For some reason, I didn't go to http://wiki2.dovecot.org/NFS until
>> now, and I'm starting to get worried ...
>>
>> The plan was to have multple servers (MXes) receiving mail, and
>> delivering via LMTP to multiple backend dovecot servers (with amavis
>> in front of dovecot; LMTP both sides). Then we'd have multiple servers
>> for clients to use IMAP or POP3.
>>
>> This is more or less how the system already works, except with Courier
>> IMAP, and postfix on the backends, delivering to maildirs with procmail.
>>
>> But with the recommendation to use the Director for both IMAP/POP3 and
>> LMTP - that starts to sound like I need a whole bunch more servers to
>> run Directors and proxies, and even then it might not be a good idea
>> to have different servers running lmtp and imap/pop.
>>
>> One possible mitigating point is that our 'load balancing' is DNS
>> round-robin, so a given client will probably stick with a single
>> imap/pop server anyway, but if the user has multiple clients
>> (desktop/mobile etc) then they may still hit different servers.
>>
>> Can someone clarify best practice for a setup needing multiple servers
>> for load balancing and redundancy?
>>
>> Is Courier already likely to have been suffering these problems?
>>
>> Oh, the NFS server is a NetApp Filer, if that matters.
>>
>> I'm using dovecot 2.2.9 from debian wheezy backports, in order to get
>> the quota policy daemon support.
>>
>> Thanks,
>> Richard