Re: replacing dovecot POP3 with qpopper (1st post)

Timothy Meader wrote:
> Wait, so are you saying that on a single system, with 5000 users, that 
> dovecot's POP3 implementation was even faster than qpopper in server 
> mode? If this is true, I might consider switching our POP servers here 
> on center (funnily enough, the same NASA center that an earlier 
> responder to this thread works at) to an all dovecot implementation 
> instead of a hybrid qpopper 4.1/dovecot beta 8 (which incidently has 
> been working fine). There's 3 boxes with roughly 2000 on each.

Yes that's correct, we were running qpopper in server mode with 
fast-update, etc. And not just a little faster, much faster. The system 
load avg went from 3 or 4 down to 1 and has stayed there with dovecot. 
We have mailboxes ranging in size from 0 to 100mb, with lots of mail 
left on the server. Dovecot handles about 10,000 pops an hour. The speed 
is due to the indexed mboxes, caching and less i/o. However, dovecot 
works a bit differently and isn't rfc compliant out of the box, so there 
are some trade-offs.

One notable trade-off with pop3, is that dovecot doesn't copy the file 
to a temp drop like qpopper does, so there's less i/o. But, by default, 
session locking is off, so 2 users can simultaneously pop the same mbox, 
  which isn't a good thing sometimes :-\. If you turn on session locking 
(which is part of the rfc for pop3), you can get into problems with your 
LDA processes waiting for Dovecot to release a lock on the mbox file if 
a client leaves a pop3 session open a long time. You can tweak timeouts 
in dovecot to work around this though. Obviously, you have to make sure 
all clients and your LDA are using compatible locks.

Ken
Pacific.Net


> Thanks in advance.
> 
> At 11:16 AM 6/2/2006, Ken A wrote:
>> Obantec Support wrote:
>>> Hi Ken
>>> I cannot live with the file .lock problem beta8 is supposed to fix 
>>> but so
>>> far Timo has not come up with a reason for beta8 not running on my mail
>>> server.
>>> if he can resolve the issue then i will stay with dovecot as its 
>>> easier to
>>> have the 1 system set-up. I currently only have around 200 mbox POP3 
>>> users.
>>
>> We'd used qpopper for 9 years, and had very few problems with it. It 
>> logs some spurious errors now and then that generate questions on this 
>> list, but the answer is usually 'read the faq'. 200 mbox users should 
>> be a perfect fit for qpopper.
>>
>> Ken
>> Pacific.Net
>>
>>> Mark
>>> ----- Original Message ----- From: "Ken A" <[email protected]>
>>> To: "Subscribers of Qpopper" <[email protected]>
>>> Sent: Thursday, June 01, 2006 5:11 PM
>>> Subject: Re: replacing dovecot POP3 with qpopper (1st post)
>>>
>>>> Just went the other way, and won't be back to qpopper unless it gets
>>>> indexed mboxes. I still like qpopper, but it's just too slow for > 5000
>>>> users on a single box. Even with all the speed tweaks you can do with
>>>> qpopper, with lots of users leaving mail on the server, dovecot is much
>>>> faster and has been very reliable - so far!
>>>>
>>>> Ken A
>>>> Pacific.Net
>>>>
>>>> Obantec Support wrote:
>>>>> Hi
>>>>>
>>>>> i am having lots of problems with dovecot as a POP3 server with file
>>> locking
>>>>> and the latest beta8 that is supposed to cure this will not run on my
>>> live
>>>>> servers but is fine on a test box.
>>>>>
>>>>> just built qpopper 4.0.8 on the test box and it seems fine. has anyone
>>>>> turned off POP3 in dovecot and used qpopper as their POP3 server?
>>>>>
>>>>> Mark
>>>>
>>>> -- 
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>>>>
> 
> ---
> Tim Meader
> CNE Internet Services
> NetCommerce Corporation
> [email protected]
> (301) 286-8013