Re: dovecot pre-install issue

[soumi...@iitk.ac.in]

Hi,

Thanks for the information. But still not sure about which dovecot 
version to choose. Any more help from developers/gurus can be a help. I 
am open to dovecot enterprise release, if it can satisfy my queries.


Regarding dovecot director, I am presently planning for option1, you 
have mentioned.


1) 200,000 IOPS (my next 5 years requirement) is possible with NFS, as 
claimed by EMC, Netapp; and I am planning to go for it. I am not in 
favour of NFS with dovecot, but out existing setup is based on NFS and 
migration will be easy. I am open for any improved storage solution 
instead of NFS.


2) I guess, the partitioning of users requires a careful planning due to 
different quota demand. presently I am trying to avoid this.


Any help in choosing appropriate dovecot version is appreciated.

Soumitri Mishra
http://home.iitk.ac.in/~soumitri/



Hi,

I understand your concerns about new versions and bug fixing, but 
after running this system for more than 3 year, trying to keep up to 
date all the time… needed a rest. That why we moved to the “out of the 
box” version, and let’s see. And it works.


About the director. There is 2 ways to use it:

1. you have multiple front end for some NFS or other single storage, 
it should balance the load between them. I tried it, but EMC, NetApp 
or other wouldn’t handle the IO/s, and that’s where there must be some 
limitations in remote FS (mainly on indexing).


2. you spread your users between 2 or more storage machines (that’s 
what we do, 12 of them currently) that each run dovecot. You can 
define in you DB the IP where your user’s mail is stored, and the 
director will redirect whatever protocol (IMAP. POP3, LMPT, Sieve) to 
the machine where the user belong. When we did the move from NFS to 
that solution, the load on all the servers were reduce by at least 50 
to 60%… if not more. And it allowed us to move from 7 webmail/pop3 
front end to 2, and 5 MXs to 2,  using 2.2.10 from CentOS 7.


About the new features… well it does look good. But 2.2.10 still allow 
you to run remote doveadm commands, so not ready to move yet. Even 
though I do like it, but so much to do, and so little time to do it...


Regards,

Re: dovecot pre-install issue

[Thierry de Montaudry]

> On 16 Nov 2016, at 13:32, soumi...@iitk.ac.in wrote:
> 
> Hi,
> 
> Thanks for the reply. I guess RHEL choose v2.2.10 
>  as it is a 
> good release with all the things working.
> 
> My source of confusion are from 
> 1) http://dovecot.org/oldnews.html 
> I have gone through each release update news. Lots of work and bug fix after 
> v2.2.10 , got 
> me confused. 
> E.g. in v2.2.13 has a fix " copied below"
>  
> director was somewhat broken when there were exactly two directors
> in the ring. It caused errors about "weak users" getting stuck.
> 2) http://wiki2.dovecot.org/Design/DoveadmProtocol/HTTP 
> 
> An interesting feature to explore post setup. 
> With thanks & regards,
> Soumitri Mishra
> http://home.iitk.ac.in/~soumitri/ 
> On Wednesday 16 November 2016 04:31 PM, Thierry de Montaudry wrote:
>>> On 16 Nov 2016, at 11:06, soumi...@iitk.ac.in  
>>> wrote:
>>> 
>>> Hello all,
>>> 
>>> I am going for a dovecot director based setup (2 director+ 2 imap), more 
>>> imap servers will be added later  depending on demand/load. Presently I 
>>> have 12000+ dovecot users with Maildir quota varying from 1 GB to 20GB. 
>>> (peak hour IOPS 5+)
>>> 
>>> I am having 2 options in choosing dovecot version.
>>> 
>>> 1) Old stable release. I.e RHEL, with prebuilt binary. This will be having 
>>> less trouble in managing. Why RHEL still using version 2.2.10.
>>> 
>>> 2) Latest release with best features and lesser known bugs. I.e CentOS7 
>>> with with latest compiled version. I have to be more involved if a bug is 
>>> found.
>>> 
>>> I will prefer a less admin work after the setup, with all/most features 
>>> working.
>>> 
>>> If you have a recent similar setup/dovecot gurus, Pl. suggest.
>>> 
>>> With thanks & regards,
>>> 
>>> -- 
>>> 
>>> Soumitri Mishra
>>> http://home.iitk.ac.in/~soumitri/ 
>> Hi,
>> 
>> Running since about 6 month a new setup with 2 directors and 12 
>> IMAP/POP3/LMTP/Sieve servers for mail storage (Maildir), to handle  500K+ 
>> users, all straight of CentOS 7 (good old yum and dovecot 2.2.10). It works 
>> very well, install is straight forward, event though it needs a bit of 
>> optimisation for this kind of traffic. Each user is assigned an IP for the 
>> redirection, which dovecot handles very well. And the deployment of new 
>> storage machine can be done in less than 30mn.
>> I didn’t have any problem with bugs up to now. But knowing that most access 
>> is done via a webmail interface (Roundcube) or POP3, we are not confronted 
>> with specific clients and IMAP problems you see now and then.
>> 
>> Hope this help. Regards,
>> 
>>  Thierry
>> 
>> 
> 

Hi,

I understand your concerns about new versions and bug fixing, but after running 
this system for more than 3 year, trying to keep up to date all the time… 
needed a rest. That why we moved to the “out of the box” version, and let’s 
see. And it works.

About the director. There is 2 ways to use it:

1. you have multiple front end for some NFS or other single storage, it should 
balance the load between them. I tried it, but EMC, NetApp or other wouldn’t 
handle the IO/s, and that’s where there must be some limitations in remote FS 
(mainly on indexing).

2. you spread your users between 2 or more storage machines (that’s what we do, 
12 of them currently) that each run dovecot. You can define in you DB the IP 
where your user’s mail is stored, and the director will redirect whatever 
protocol (IMAP. POP3, LMPT, Sieve) to the machine where the user belong. When 
we did the move from NFS to that solution, the load on all the servers were 
reduce by at least 50 to 60%… if not more. And it allowed us to move from 7 
webmail/pop3 front end to 2, and 5 MXs to 2,  using 2.2.10 from CentOS 7.

About the new features… well it does look good. But 2.2.10 still allow you to 
run remote doveadm commands, so not ready to move yet. Even though I do like 
it, but so much to do, and so little time to do it...

Regards,

Re: dovecot pre-install issue

[Michael A. Peters]

On 11/16/2016 01:06 AM, soumi...@iitk.ac.in wrote:

Hello all,

I am going for a dovecot director based setup (2 director+ 2 imap), more
imap servers will be added later  depending on demand/load. Presently I
have 12000+ dovecot users with Maildir quota varying from 1 GB to 20GB.
(peak hour IOPS 5+)

I am having 2 options in choosing dovecot version.

1) Old stable release. I.e RHEL, with prebuilt binary. This will be
having less trouble in managing. Why RHEL still using version 2.2.10.

2) Latest release with best features and lesser known bugs. I.e CentOS7
with with latest compiled version. I have to be more involved if a bug
is found.

I will prefer a less admin work after the setup, with all/most features
working.

If you have a recent similar setup/dovecot gurus, Pl. suggest.

With thanks & regards,



I only run small server but I use CentOS and build the most recent 
myself and do not have many issues.


CentOS 7 dovecot btw is same as RHEL 7 dovecot as far as I know.

Re: dovecot pre-install issue

[soumi...@iitk.ac.in]

Hi,

Thanks for the reply. I guess RHEL choose v2.2.10 
 as it 
is a good release with all the things working.


My source of confusion are from

1) http://dovecot.org/oldnews.html

I have gone through each release update news. Lots of work and bug fix 
after v2.2.10 
, got me 
confused.


E.g. in v2.2.13 has a fix " copied below"


director was somewhat broken when there were exactly two directors
  in the ring. It caused errors about "weak users" getting stuck.

2) http://wiki2.dovecot.org/Design/DoveadmProtocol/HTTP

An interesting feature to explore post setup.

With thanks & regards,

Soumitri Mishra
http://home.iitk.ac.in/~soumitri/

On Wednesday 16 November 2016 04:31 PM, Thierry de Montaudry wrote:

On 16 Nov 2016, at 11:06, soumi...@iitk.ac.in wrote:

Hello all,

I am going for a dovecot director based setup (2 director+ 2 imap), more imap 
servers will be added later  depending on demand/load. Presently I have 12000+ 
dovecot users with Maildir quota varying from 1 GB to 20GB. (peak hour IOPS 
5+)

I am having 2 options in choosing dovecot version.

1) Old stable release. I.e RHEL, with prebuilt binary. This will be having less 
trouble in managing. Why RHEL still using version 2.2.10.

2) Latest release with best features and lesser known bugs. I.e CentOS7 with 
with latest compiled version. I have to be more involved if a bug is found.

I will prefer a less admin work after the setup, with all/most features working.

If you have a recent similar setup/dovecot gurus, Pl. suggest.

With thanks & regards,

--

Soumitri Mishra
http://home.iitk.ac.in/~soumitri/

Hi,

Running since about 6 month a new setup with 2 directors and 12 
IMAP/POP3/LMTP/Sieve servers for mail storage (Maildir), to handle  500K+ 
users, all straight of CentOS 7 (good old yum and dovecot 2.2.10). It works 
very well, install is straight forward, event though it needs a bit of 
optimisation for this kind of traffic. Each user is assigned an IP for the 
redirection, which dovecot handles very well. And the deployment of new storage 
machine can be done in less than 30mn.
I didn’t have any problem with bugs up to now. But knowing that most access is 
done via a webmail interface (Roundcube) or POP3, we are not confronted with 
specific clients and IMAP problems you see now and then.

Hope this help. Regards,

Thierry

Re: dovecot pre-install issue

[Thierry de Montaudry]

> On 16 Nov 2016, at 11:06, soumi...@iitk.ac.in wrote:
> 
> Hello all,
> 
> I am going for a dovecot director based setup (2 director+ 2 imap), more imap 
> servers will be added later  depending on demand/load. Presently I have 
> 12000+ dovecot users with Maildir quota varying from 1 GB to 20GB. (peak hour 
> IOPS 5+)
> 
> I am having 2 options in choosing dovecot version.
> 
> 1) Old stable release. I.e RHEL, with prebuilt binary. This will be having 
> less trouble in managing. Why RHEL still using version 2.2.10.
> 
> 2) Latest release with best features and lesser known bugs. I.e CentOS7 with 
> with latest compiled version. I have to be more involved if a bug is found.
> 
> I will prefer a less admin work after the setup, with all/most features 
> working.
> 
> If you have a recent similar setup/dovecot gurus, Pl. suggest.
> 
> With thanks & regards,
> 
> -- 
> 
> Soumitri Mishra
> http://home.iitk.ac.in/~soumitri/

Hi,

Running since about 6 month a new setup with 2 directors and 12 
IMAP/POP3/LMTP/Sieve servers for mail storage (Maildir), to handle  500K+ 
users, all straight of CentOS 7 (good old yum and dovecot 2.2.10). It works 
very well, install is straight forward, event though it needs a bit of 
optimisation for this kind of traffic. Each user is assigned an IP for the 
redirection, which dovecot handles very well. And the deployment of new storage 
machine can be done in less than 30mn.
I didn’t have any problem with bugs up to now. But knowing that most access is 
done via a webmail interface (Roundcube) or POP3, we are not confronted with 
specific clients and IMAP problems you see now and then.

Hope this help. Regards,

Thierry