How many uses for multi-server install?

[jterhune]

I currently manage a single server install on an ESX host using SATA SAN storage. We support approximately 8000 accounts (6000 have logged in within the last 90 days). We've begun to experience some issues with sluggishness both on the web UI and command line management.

I was hoping for some input as to whether or not we should be considering a multi-server install at this point. Where are the general recommended cutoff points for adding more servers to an install? Our accounts aren't used terribly heavily (they are students, not business users).

Thanks for any advice.

[raj]

There is no straight forward way to tell when you need to go from single to multi servers.
Generally speaking if running at 80% resources (CPU, RAM) for more than 12 hours out of 24 hours u have reached full capacity of your hardware. This is our personal yardstick.
On the other hand we do want to run at 80% or more efficiency to get full use of the expensive hardware.
* Hard Drive (i/o) bottleneck can occur even much lower % you need to rule that out separately

Multi-server solution (OSS version) will give you protocol (MX in and out, SMTP in and out) redundancy and mailbox scalability (no mailbox clustering in OSS)

Minimum I like to put is:

2 MX
2 Mailboxes
2 LDAP (master + slave)
1 Proxy (optional)

if you using ESX then LDAP and Proxy only need very little resources for VM's so you can really have the true multi server without breaking the bank

You will see increase in web client performance and IMAP with multi-server, coz its sharing the load


Raj