Re: [gentoo-user] Server Mirroring...

[Sascha Lucas <sascha.lucas@rus.uni-stuttgart.de>]

Hi Mal,

> I run a Apache2 webserver and Postfix as per the virtual mailhost
> guide...
>
> For resilience I would like to have two gentoo boxes doing these tasks
> for load balancing / redundancy - how can this be achieved?  Is there a
> tool that will allow replication of the config files / mysql stuff to
> allow the boxes to basically be a cluster ?

Thats not so easy to answer. Different solutions exists, each with pros 
and cons. It also depends heavily on the professional grad your solution 
should be.

You can solve this at different Levels: Hardware, OS, application. 
Hardware is expensive. OS far from perfect (i.e. openssi, openmosix). 
Applications must be cluster aware, moast aren't.

Do you mean http://www.gentoo.org/doc/en/virt-mail-howto.xml? If so you 
have to manage a bunch of apps: postfix, mysql, cyrus, apache.

Just some keywords:

easy with postfix: DNS round robin (solution inside DNS Server, nearly 
all MTAs are aware of this)

mysql: not "multi master" ready, just redundancy "master->slave", try 
postgres

apache: behaves in sens of "read only" -> LVS

cyrus: moast difficult part (shared storage/CFS,???) -> 
NAS|SAN+CFS+LVS+?dono?

Cluster/HA is a complex area. Perhaps you want a simple not so perfect 
solotion? Try periodicaly rsynced standby with manual switch over.

Sascha.
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