Re: [webmin-l] while we're at it (cyrus imapd)

[Joe C. <jo...@sw...>]

Craig White wrote:
> On Mon, 2005-09-19 at 13:14 -0500, Joe Cooper wrote:
> 
>>Yes.  Dovecot is not a "drink the Kool-aid" kind of server, the way 
>>Cyrus is.
> 
> ----
> that's a rather extreme metaphor Mr. Jones ;-)

I'm pretty sure I got the metaphor from you, Craig.  Really, I think 
read it in one of your posts a few days ago and immediately thought, 
"Perfect metaphor!"  ;-)

> the fact is that mailboxes, seen messages, duplicate message supression
> etc. are indeed indexed using db's which make it so darn fast. I have no
> test data comparing dovecot performance to cyrus so I let your 5%
> performance claim go since I have no way of proving or disproving and I
> suspect that your 5% claim was just simply a uswag.

Hold up...I said the performance difference for the whole system, 
including SpamAssassin and ClamAV, would only be about 5% faster with 
Cyrus, if any.  I didn't say that Cyrus by itself was only 5% faster 
than Dovecot by itself for any particular task (though it might not even 
be as fast...I don't know...I've never seen benchmarks of Dovecot vs. 
Cyrus, though I've seen both compared to all of the "slow" POP and IMAP 
servers).  What I said was that Cyrus can't make SpamAssassin or ClamAV 
take less resources, and in any mail server running those services, they 
are where almost /all/ resources go.  I'm sure that Cyrus is extremely 
fast and wonderful in every possible way and I have no inclination to 
criticize it (though I do readily admit why I wouldn't choose it).  I'm 
just saying that no amount of microtuning of the delivery agent or the 
retrieval server is going to make the real resource hogs disappear. 
Dovecot is blazing fast, and I'm sure Cyrus is too (possibly more 
blazing fast even), but on my mail servers, when I look at CPU/memory 
usage Dovecot isn't even a blip on the radar, while anti-spam and AV are 
at the top of the list.

Nobody is criticizing your religious beliefs, Craig.  Certainly not me. 
  I respect all faiths, from Emacs to Vim and everything in between.  ;-)

> Likewise using cyrus-imapd, sieve scripts are all previously bytecoded
> (compiled) for faster performance rather than shell execution of
> procmail. Perhaps Joe wants to toss another 5% figure at that too.

Nope.  I just want to toss in another reminder that it just doesn't 
matter.  Procmail is 1% of my CPU usage on my most heavily loaded mail 
server and Dovecot is about the same.  SpamAssassin is 30% and ClamAV is 
probably 10%.  When I look at those numbers I couldn't care less whether 
Procmail is being inefficient because a shell is spawned for every 
message.  Even if Cyrus and Sieve are 5 times faster, I'll still only 
save .8% CPU time over Procmail.  I'm just not gonna sweat over some 
pocket change.  ;-)

I'll concede that lack of caching and good indexing in some POP/IMAP 
servers can lead to sluggish client-side response...but Dovecot is not 
one of those servers.  uw doesn't take much CPU or memory, but is very 
slow on large mailboxes.  Dovecot is very fast and still doesn't take 
much CPU or memory.  And you get to keep standard Maildir or mbox 
spools, so all mail tools will continue to work as they always have.  I 
consider that a win.  The lack of which is why Cyrus is a "drink the 
Kool-aid" kind of product.  You've gotta migrate your whole tool-chain 
in order to use Cyrus.

> While you probably can use UserMin to access maildir stores, you aren't
> going to benefit from subscription lists, seen state or imap flags
> without an IMAP login and if you had an IMAP login, then cyrus-imapd
> would work as well...but an IMAP login isn't part of the feature set of
> UserMin.

But it is.  I mentioned that when this came up a few days ago.  Usermin 
supports the following folder types:

- System folders like Inbox, Drafts and Sent Mail that always exist.
- Folders in in the mail directory that can be created or deleted by 
Usermin.
- Other files or directories that can be managed as folders by Usermin.
- POP3 accounts on other servers that can be treated as folders.
- IMAP accounts on other servers.
- Composite folders, which combine two or more other folders into a 
single list.
- Virtual folders, which contain a selection of mail from others.

Note that one of those is IMAP, and thought it doesn't state it 
explicitly, local Maildir folders are also supported.  It doesn't handle 
the .subscriptions file yet, as far as I know, but there's no reason why 
it couldn't.  Seems like it would actually be pretty easy to implement...

I'm sure Cyrus is a very fine package.  I'm not just going to be using 
it, unless I find that Dovecot is inadequate (and I also find that Cyrus 
is adequate for the situation that proved Dovecots downfall).  ;-)

Regards,
Joe