Nick Steel writes:
I'd be interested in hearing about the maximum number of active sessions,
memory and processor utilization for high load servers that people are
running.
Under Linux, Courier-IMAP's data segment is about 2MB after opening a folder
with 2,000 messages. With a more reasonable scenario of a 100-message
folder, the size of the data segment is about 800Kb. So, you can expect
that a server with 1GB of RAM will have enough RAM for at least 500
simultaneous IMAP sessions. A single session should never have more than 10
files open at the same time, so the server should be capable of handling
5,000 open files.
You definitely want to throw enough extra RAM for a large NFS cache. With
the mail store on NFS, there is no local disk I/O to worry about, so you'll
only need to figure out how much network bandwidth you'll need. CPU load
should not be a problem unless you've got a bunch of people scanning folders
with tens of thousands of messages. The configuration file allows some
CPU-intensive IMAP operations to be disabled or not even advertised to the
IMAP client.
2 messages in net.sourceforge.lists.courier-users[courier-users] Re: Capacity planning...
