multiple kolab servers

[Jan Gerle]

Hi Stéphane & all

Stéphane Konstantaropoulos schrieb:

> Do you know if there is a document somewhere that explains how to set up 
> multiple kolab servers?
> 
> I wonder especially how is works for the emails: what server must be 
> configured as the MX and how it redirects to the server that holds the email 
> account for the user. Is there anything specific to do to postfix or to cyrus 
> to that, or is it completely automatic?

There are several relevant points for using multiple servers, depending
on what you are up to. Basically Kolab consits of these parts:
- smtp server (postfix, MTA)
- antispam and -virus (SpamAssassin, amavisd
- imap server (cyrus, MDA)
- directory server (openldap)
(- and some webstuff, ftp etc.)

Using multiple SMTP servers is quite easy: your second MTA (e.g. MX 20
in DNS) just needs to know where to deliver mail. Either it delivers
directly to Cyrus, e.g. on your primary machine or it forwards to your
primary or even on-site SMTP. This mainly depends on how your inbound
mail is directed and where/how you would like to scan for virii and
SPAM. You can even have a dedicated machine for scanning. This is all
postfix related and not kolab itself. AFAIK it is not configurable via
Kolab webfrontend, only through proper service config files (postfix
main.cf etc.).

If your focus is more on load balancing the users mailboxes you are up
to Cyrus Murder (IMAP storage over multiple backend servers = back end)
and Aggregator (IMAP load balancer = front end where users connect their
MUA to).

Usefull links:
http://cyrusimap.web.cmu.edu/imapd/install-perf.html
http://cyrusimap.web.cmu.edu/imapd/install-murder.html
http://cyrusimap.web.cmu.edu/ag.html

-> These tools are part of the Cyrus IMAP server, but _not_ explicitly
of Kolab, allthough they are installed. I do not know how well the Kolab
webfrontend cooperates with the config changes needed to get
Murder/Aggregator to work (my guess: it does not).

> Then, as for the client, if his/her email account is on a specific server, 
> does he/she have to set up the email client software to query that server and 
> not the master?

See Cyrus Murder and Aggregator: client MUA connects to Aggregator,
which transparently proxies to the next free IMAP (or POP) backend.

> Is it useful to have multiple servers as a whole? (I have lots of users here)

As written above you can have various different multiple servers.
Operation with multiple SMTP servers is quite easy, Cyrus
Murder/Aggregator is more advanced. For load balancing openldap you
could use an IP sprayer - I ever tried and only read about that. You can
also take a look at LDAP replication/distribution to use multiple LDAP
servers and then configure each Cyrus backend server to use one of those
(IMAP1 -> LDAP1, IMAP2 -> LDAP2 etc. pp.).

Some links I found with a quick Google lookup:
FAQ: flexible administration of multiple kolab servers
http://lists.kde.org/?l=kroupware&m=103336398827374&w=2
The Big Kolab Kontact Interview - Part I
http://mail.kde.org/pipermail/dot-stories/2005-January/000403.html
-> they say it is possible, but they do not tell how :)

HTH,
Jan