11.8 Trend monitoring and usage analysis

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The Exchange administrator should monitor trends to detect changes in the use and performance of the Exchange messaging environment over the course of time. The objectives of trend monitoring are:

• Early detection of messaging service degradation

• Analysis of stored performance information to identify, analyze, and react to changes

• Collection and correlation of historical data to assist with detection, analysis, and correction of systemic faults

• Comparison of actual service levels with the targets established in SLAs

• Data collection and analysis to assist with capacity planning

• Ability to forecast future growth to determine hardware and software needs

Monitoring to identify trends requires that data be collected at regularly scheduled intervals to provide the source data for producing reports. The scheduled data collection also provides the database for ad hoc queries, report generation, and analysis.

The administrator must carefully balance the quantity of collected data against the impact that the data collection will have on network and server performance. In general, it is best that the combination of health and trend monitoring should add no more than a 3% to 5% performance penalty during normal operation. Unlike health monitoring where a backup monitoring site is recommended, a backup monitoring site is not recommended for trend monitoring, because it will cause an unnecessary load on the network and the servers.

The Exchange administrators should establish policies regarding the type and quantity of data that should be collected for trend monitoring. Tables 11.2 through 11.4 describe some recommended counters for Exchange messaging data collection. These should be periodically reviewed and adjusted to ensure that they are providing the necessary information needed for reporting and analysis, without placing an unnecessary adverse strain on the network and Exchange servers.

Table 11.2: System Resource Availability Counters

Object	Counter
Memory	% Committed Bytes In Use
Memory	Pages/sec
Paging File	% Usage
Processor	% Processor Time
SMTP Server	Message Bytes Sent/sec

Table 11.3: Disk Space Utilization Counters

Object	Counter
LogicalDisk	% Free Space
LogicalDisk	Free Megabytes
MSExchangeIS Mailbox	Total Size of Recoverable Items
MSExchangeIS Public	Total Size of Recoverable Items

Table 11.4: Messaging System Utilization Counters

Object	Counter
MSExchangeIS	Active User Count
MSExchangeIS	RPC Requests
MSExchangeIS	User Count
MSExchangeIS Mailbox	Messages Delivered/min
MSExchangeIS Mailbox	Messages Sent/min
MSExchangeIS Public	Messages Delivered/min
MSExchangeIS Public	Messages Sent/min
MSExchangeIS MTA	LAN Receive Bytes/sec
MSExchangeIS MTA	LAN Transmit Bytes/sec
MSExchangeIS MTA	Message /Sec
MSExchangeIS MTA	Message Bytes/Sec
SMTP Server	Message Bytes Received Total
SMTP Server	Message Bytes Received/sec
SMTP Server	Message Bytes Sent Total
SMTP Server	Message Bytes Sent/sec
LAN, local area network; RPC, Remote Procedure Call; SMTP, Simple Mail Transfer Protocol

The Exchange administrator should regularly analyze the usage of the Exchange messaging environment. This can be done most easily by periodically logging and analyzing the message traffic on a sample set of Exchange servers. These logged messages should be examined to determine the average size of messages, the typical number of recipients, the location of the recipients (e.g., internal Exchange users, internal users on other mail systems, external Internet users), the type and size of attachments, and the typical message attributes. This information can then be used to improve the accuracy of capacity planning. It is also often useful to let the funding business units understand how the messaging system is being used.

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