[cobalt-users] Help me to Divide and Rule...

["Yiannis Costopoulos" <yiannis@xxxxxxxxxxxxx>]

Hi,

I am trying to create a sort of High Availability system with two RaQ4s
running 550OS.

As I have limited resources I decided to follow the advice of "Divide
and Rule". Therefore I will "split" the jobs between the two RaQs.

I am thinking to have the following configuration:

    +-------------------------+1st RaQ
+---+ 192.168.0.10 eth0       |
|N  | 192.168.0.12 eth0 alias |
|U  | 192.168.1.1  eth1       |
|L  | Primary DNS             |     +--------------+     +------------+
|L  | MX                      +-----+ LAN SWITCH 1 +-----+ FIREWALL 1
+--->
|   | MySQL                   |eth0 +---+--------+-+     +-+----+-----+
TO   
|M  | Backup Web Server       |           |       \        /    |
ISP 
|O  +-+-----------------------+           |        \      /     |
|D    |eth1                               |         \    /      |
|E    |                                   |          \  /       |NULL
|M    |rsync for Web data                 |           \/        |MODEM
|     |MySQL Repliaction                  |           /\        |HEART
|H    |                                   |          /  \       |BEAT
|E    |eth1                               |         /    \      |
|A  +-+-----------------------+2nd RaQ    |        /      \     |
|R  | 192.168.0.11 eth0       |           |       /        \    |
|T  | 192.168.0.13 eth0 alias |eth0 +---+--------+-+     +-+----+-----+ 
|B  | 192.168.1.2  eth1       +-----+ LAN SWITCH 2 +-----+ FIREWALL 2
+--->
|E  | Web Server              |     +--------------+     +------------+
TO
|A  | Secondary DNS           |
ISP
|T  | Backup MX               |
+---+ Backup MySQL            |
    +-------------------------+

As you can see from above, I try not to have a single point of failure.
Web pages and contents of Raq2 are rsync'd to Raq1. MySQL (4.0.18) data
on Raq1 are replicated to Raq2.The two RaQs listen and check each
other's heartbeat. When they cannot hear it, the try pinging through
eth1. If there is no reply, then it takes over the alias IP of the other
Raq. Web and MySQL services are on the alias IPs.

At the moment I am trying to solve the problem I have with the two RaQs.
This is where I need your advice. I want Raq1 to be Web server, so I
create site into it. I want Raq2 to be MX server, do I need to create
the same sites there too? Is there a way to create a site in Raq1 and
automatically it gets created in Raq2 (I use rsync, but I think that
it's more than copying across /home/.sites/ )? How can I make Raq1 to be
Backup MX? What settings do I need to use? How is it going to relay the
email to Primary MX when that comes back up?

Any help, ideas or experiences are more than welcome.

TIA
Yiannis Costopoulos