Buffers

The following are the important buffer counters for Microsoft Exchange Server.

Object	Counter
Database: Information Store	File Bytes Read/sec
	File Bytes Written/sec
	Cache % Hit
Database: Directory	File Bytes Read/sec
	File Bytes Written/sec
	Cache % Hit

Depending on your usage patterns, you might be able optimize the use of server memory by adjusting the number of information store buffers. Monitor the % Buffer Cache %Hit counter. If it is consistently very close to 100 percent, try decreasing the number of buffers. You should also monitor the information store disk activity. If the activity doesn't increase, your setting is correct. However, if you notice that the cache hit rate is less than 95 percent, try increasing the number of buffers. As long as the paging activity does not increase, the setting is correct. You should use caution when changing these settings. Make only small adjustments, and monitor the results until you are confident the changes you have made work appropriately.

Recommendations

• Consider using perfwiz -v to adjust your information store buffer usage if the cache hit rate is very high or very low.
• If you cannot find a happy medium for this setting, you probably need to add more memory.

The Network Interface object can be obtained by installing the Microsoft Windows NT Resource Kit. If your network connection is a point-to-point link, the counters described below show all traffic on the link. If the connection is a LAN, these counters will show the traffic to and from the server you are monitoring.

Object	Counter
Network Interface	Bytes Received/sec
	Bytes Sent/sec
	Packets Received/sec
	Packets Sent/sec

If you know the capacity ratings of your network and network interface card (NIC), you can compare these ratings to the values for the Network Interface counters shown above and determine how close to capacity you are operating. For a more complete overview of network traffic, you also can use the Network Monitor tool available with Microsoft Systems Management Server (SMS). Note that Network Monitor is a stand-alone tool. You do not have to have other SMS components installed to run Network Monitor.

If you discover that the server is operating at or near network capacity, you can upgrade the network speed (for example, by moving from a 10 MB Ethernet to a 100 MB Ethernet network, or moving from a 64 KB line to a T1 line). You might also want to consider using multiple Ethernet connections for the server or multiple 64 KB lines, rather than one faster connection or line. Consider faster links, multiple interfaces, and multiple links.