Multiple servers and NFS

[Eduardo Ramos]

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