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List:       info-cyrus
Subject:    Re: [POLL] virtual domains and Murder
From:       Fabian Fagerholm <fabbe () paniq ! net>
Date:       2002-07-24 21:15:03
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First, a great thank you for your work on virtdomains.

On Wed, 2002-07-24 at 22:38, Ken Murchison wrote:
> I started thinking about Murder and virtual domains.  Since Murder was
> designed to support a single unified mailbox namespace, does it make
> sense to use Murder for virtdomains?
>=20
> If an admin needs more than one box to support the his/her domains, why
> not just use one server (or Murder) per domain?  Or are people intending
> to have separate backends for each domain, and the frontend(s) simply
> proxy/redirect the user to the correct backend?

IMO, it does make sense to have Murder support virtdomains. And in a
sense, if you expand the virtdomains concept to Murder, you would end up
with a scheme where you can have a Murder of Murders - ie. virtmurders.

This would work as follows: You have a number of backends and a number
of frontends. For a given domain, at least one backend and at least one
frontend would be used. When the domain grows to proportions that render
the current number of back- and frontends insufficient, you could simply
add another back- or frontend to handle the domain in question.

Any given frontend and any given backend in the Murder could handle any
given domain - but all frontends and all backends in the Murder would
not neccessarily handle all domains. For example, if you had three
backends and eight frontends, the domain example1.com could be handled
by backends number 1 and 2, and frontends number 1-4 inclusive, while
the domain example2.com could be handled by backends number 2 and 3 and
frontends number 3-6 inclusive - thus example1.com would be handled by a
different part of the Murder than example2.com. Those parts could be
called "virtual Murders", and the entire system a "Murder of (virtual)
Murders". (The point being that you still run one mupdate master.)

I don't know if this would require any substantial changes to the Murder
code, but (clueless as I am) I would think you just have to put the
right things in your DNS records to make it work for the clients
connecting to the front-ends, and then configure front- and backends to
handle the correct domains. Changes, I assume, would be primarily to
mupdate + friends to support breaking the namespace into domains and
passing the domain part around (?).

An important feature to go with this would be good support for moving
mailboxes between backends. Thus, you could fine-tune your system by
manually moving mailboxes to distribute the load evenly on the backends.
Also, you could retire a backend by moving all the boxes off it to
another backend and remove the retired backend from the Murder.

> user@domain userids:  traditional Murder, where both frontends and
> backends know how to handle the virtdomains

This would be just fine. Having domain-from-ip would be an added bonus
but I think user@domain is perfectly acceptable.


Again, great job on this stuff.

Cheers,
Fabian Fagerholm


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