Determine optimal number of concurrent sessions

Question

How do I determine the optimal number of concurrent network and local processes
for my system?
<P>
On Unix Messaging Servers, there is a configuration option (select "System
Configuration") that allows an administrator to specify the maximum number of
concurrent local and network processes. On NT, each process is a thread, so there is a differentiator for
IMAP/POP.
<P>
Network processes are IMAP, POP, and SMTP-Deliver. If you set this number to 32,
there will be 32 processes available each for IMAP, POP, and SMTP-Deliver.
If all three modules use their maximum allotment of processes, there will be a
total of 96 processes for IMAP, POP, and SMTP-Deliver.
<P>
Local processes are SMTP-Accept, SMTP-Router, Error-Handler, Mailbox-Deliver,
and other processes that process mail within the Messaging Server. If you set
this number to 16, there will be 16 processes available for each of these
modules.
<P>
Determining an optimal number for each of these settings requires analysis of
your configuration and users, as well as some testing. To find a number to
start with, use these directions. Then try running your server and monitor the
performance. If you want to optimize the numbers, change them a little bit at a
time and note if the performance improves or not. After trying a few different
numbers, you will probably be able to determine a range that works for your
system. Remember to leave yourself a buffer of extra available processes to
handle peak traffic, or spikes in traffic that are unexpected.
<P>
If you have a SMTP service only, then the maximum number of concurrent network
processes needs to be around the maximum number of simultaneous messages sent
plus the number of processes needed to deliver messages. For example, if you have 100
users per second attempting connections, network processes will be
100 + 10-50 delivery agents. This value is dependent upon how much mail you send.
<P>
If this machine is also used for message pickup,(POP3/IMAP4), you need to
consider these network processes, too. For example, 1000 IMAP sessions adds 1000
to the network processes, while POP would add about one quarter to one half as much.
<P>
Be careful configuring the maximum number of concurrent local processes. If
they are configured too high then you have I/O race conditions with processes
trying to compete for I/O and the CPU. The best approach is to start off with
around 10 and increase this value in units of 5 observing the drain rate of
message delivery.

Answer 1

Go to Performance tab and click Search Sessions. In next page dont specify anything and just click Go. It will show you all DB User Type users in Results grid. You can change that to System User Type.