Am 17.11.2011 19:55, schrieb Patrick Ben Koetter:
Well, at the moment there are 30000~ incoming mails per month,
30.000 msg overall, including spam, or filtered messages?
Yes, overall. Got this values from mailgraph...
Content filtering is CPU expensive. If you centralize the filter you
will have
to buy hardware that can filter for more than one server at the same
time AND
can deal with peak load. You will end up buying extra powerful CPUs
(including
board and RAM).
Regular servers bring 8 core CPUs, of whom most idle most of the time
on a
mail server because mail is I/O bound. There's plenty of ressources
left to
run an additional content filter.
Yeah, you're right, doesn't thought of that, yet.
Sharing Ressources
If you run a centralized content filter you don't have to worry about
knowledge distribution. All knowledge required (e.g. bayes DB,
quarantine)
resides on one server.
I don't consider this a problem either. Accessing bayes and
quarantine over a
network is easy - both can use SQL as storage. All amavis tools are
storage
agnostic. You configure the backend in amavisd and tool communication
takes
place with amavisd, which deals with backend communication.
Is it a problem when multiple amavisd instances want to write to bayes
db ore awl db at the same time?
Management
If you run n instances of amavis on n servers you will have to manage
n
configurations. No reason to put everything on a centralized server
either.
First of all there are tons of tools to deal with configuration
distribution
ranging from scp, rsyc, etckeeper, Makefiles up to heavy machinery
such as
cfengine, puppet, chef etc. pp. to help you distribute configuration.
Secondly you can provide domain and recipient specific configuration
over
network using SQL or LDAP and last, but not least, configuration
tends to
stablize after a while and you need to deal with it only rarely.
Redundancy
If you run many servers, they can take over if one dies. If you run a
central
server you will have to provide a spare server in case it dies away.
AND you
will have to keep all config and knowledge in sync.
I favor a decentralized system.
Thank's a lot for your suggestions. You helped me a lot to plan my next
setup, also tending now to decentralized system.
Best regards,
Tobias
