Hi,
we have a medium setup (8000 pop and imap users using almost every available client, 800GB of stored mails using maildir on a Celerra NFS server, with index files on local disks, and procmail for local delivery), being served by a Dell PowerEdge 2850 (2GB RAM and dual P4 Xeon 3,2GHz).
Our current not-so-high availability setup is based on a similar server with the same setup and a easy but manual process to switch from one server to another.
We are thinking about setting up some kind of serious high availability, but for every strategy we think about some problems appear, and I'd like to hear your opinions about them:
- The recommended setup, with each user being sent always to the same server, is not possible because our load balancers (Cisco Catalyst
- can't do that.
We could put both servers behind the load balancer, and keep local index files on each server. Usually the same ip we'll be redirected to the same server, so few problems will arise. When a user is sent to a new server, index will be rebuilt so performance will be bad but we should not expect other problems, right?
We could also put the index files on a nfs share. No problems, but pretty bad performance.
We could also get more ram for the servers and keep indices in memory.
How can we compare these solutions? Apart from performance, are other problems expected? Using deliver instead of procmail could improve performance?
- We've also thought about some more or less weird setups, like setting up a GFS filesystem for the index files, or setting up a proxy on every server which redirect users to their fixed server, but they seem too complex for few advantages.
Any recommendations? How are you doing this?
Joseba Torre. Vicegerencia de TICs, área de Explotación