>do there exist any solutions for clustering qmail to build high-volume-servers
>i`m looking for some tools or patches to do load-balancing, put pop-boxes on
>more than one server, use more than one smtp-server...
>help???
There are several server load balancer solutions available. I use the
'ServerIron' product from Foundry Networks (www.foundrynet.com), it seems
to perform very well. You also have Alteon (www.alteonwebsystems.com),
cisco, and others.
These boxes are regular layer-2 switches. In addition to
switching packets like other switches, they perform load balancing.
One way they can do this is to reply to ARP requests
for the IP addresses your mail server is known by on the Internet.
Your router will therefore send all incoming IP packets to the ethernet
address of the switch. The switch will pick up a packet, choose the
front-end mail processor (FEP) it thinks has the lowest load at the moment,
put that ethernet address on the packet instead of its own and put
the packet back on the wire for the FEP to pick up.
The switch also monitors the FEP's and routes connection requests to
other working servers if a FEP is discovered to be faulty. This makes error
situations and maintainance downtime invisible to the clients.
--
Gjermund Sorseth
