Using Load Simulator

If you are trying to determine the optimum number of users per server on your own, it is important to represent the users as accurately as possible. Some organizations have no idea how their user base will use Microsoft Exchange Server because they may have never had any messaging products on which to base their numbers. Other organizations will have some idea, based on previous experience, as to how their users will use a messaging platform. However, Microsoft Exchange Server may provide features and functionality that have never been available to their user community, so the organization may not fully understand what impact these new features can have.

For testing purposes, users are classified as having low, medium, and heavy usage. Initially, the users' states were as follows:

Parameter	Low-Usage User	Medium-Usage User	Heavy-Usage User

Number of non-default folders	20	40	60
Number of messages per folder	5	5	5
Number of messages in Inbox	1	4	9
Number of messages in Deleted Items folder	1	1	1

For testing purposes, we defined low-usage users as those who do the following on a daily basis:

Divide their time into an 8-hour daytime and a 4-hour nighttime.
Originate three new messages (that is, not replies and forwards) to four recipients, and save a copy of these messages in the Sent Mail folder.
Read new mail five times and old mail 12 times.
Note Reading new mail consists of opening the Inbox and reading every piece of new mail that the user has received. Reading old mail consists of selecting one folder at random and reading one message in that folder.

Testing demonstrated that light users:

Used the following commands when working with messages: Reply (10 percent of the time), Reply All (3 percent), Forward (5 percent), Move (none of the time), Copy (one of the time), and Delete (40 percent).
Loaded 25 percent of the attachments received.
Limited their Inbox to 20 messages.
Emptied their Deleted Items folder once.
Made one change to their schedule.

Medium-usage users were defined as those who do the following on a daily basis:

Divide their day into an 8-hour daytime and a 4-hour nighttime.
Compose six new messages (that is, not replies and forwards) to four recipients, saving a copy of them in the Sent Mail folder.
Read new mail 15 times and old mail 12 times.

Testing demonstrated that medium users:

Used the following commands when working with messages: Reply (15 percent of the time), Reply All (5 percent), Forward (7 percent), Move (20 percent), Copy (none of the time), and Delete (40 percent).
Loaded 25 percent of the attachments they received.
Limited their Inbox to 125 messages.
Emptied their Deleted Items folder once.
Made five changes to their schedule.

Heavy-usage users were defined as those who do the following on a daily basis:

Divide their time into an 8-hour daytime and a 4-hour nighttime.
Originate eight new messages (that is, not replies and forwards) to five recipients, saving a copy of them in the Sent Mail folder.
Read new mail 20 times and old mail 12 times.

Testing demonstrated that heavy users:

Used the following commands when working with messages: Reply (20 percent), Reply All (7 percent), Forward (7 percent), Move (20 percent), Copy (none of the time), and Delete (40 percent).
Loaded 25% of the attachments received
Limited their Inbox to 250 messages.
Emptied their Deleted Items folder once.
Made 10 changes to their schedule.

The data above generated the following computed averages:

	Light User	Medium User	Heavy User

Messages sent per day	6.7	19.8	38.6
Messages received per day	20.4	55.9	118.9

The message mix for these users was also varied. Four different message types/sizes were used: 1K, 2K, and 4K messages, plus a message with a 10K attachment. A mix of these messages was used for each user type and weighted as follows:

Message Size/Type	Light User	Medium User	Heavy User

1K message	9	7	6
2K message	(none)	2	2
4K message	(none)	(none)	1
10K attachment	1	1	1