Monitoring and Tuning Your Server

Suggested Values

Table 5.19 lists some of the counters that are generally useful for monitoring your server, with suggestions about appropriate or dangerous values. Most of these values are given in relative terms, because actual numbers vary from site to site. For example, the Computername\ Active Server Pages\ Transactions/ sec counter is not relevant to a Web site with only static content, and Computername\ Disk\ Avg Disk Bytes/Transfer is different for different kinds of controllers and drives. (Again, “Computername” is omitted, in order to conserve space.)

Table 5.19 Useful Counters for Monitoring Web Server Performance

Object:Counter	Preferred or Ideal Value
Memory\ Pages/sec	0-20 (bad if over 80; probably indicates insufficient RAM).
Memory\ Available Bytes	At least 4 MB.
Memory\ Committed Bytes	Not more than about 75% of physical memory size.
Memory\ Pool Nonpaged Bytes	Steady (slow rise may indicate a memory leak).
System\ Context Switches/sec	As low as possible.
Processor\ % Processor Time	Less than 75%.
Processor\ Interrupts/sec	Depends on processor, and on network hardware and drivers. Up to 3,500 for 90 megahertz (MHz) Pentium; more than 7,000 for 200 MHz Pentium. Lower is better. If the value is too high, try moving some hardware devices to a different server.
Processor\ System Processor Queue Length	Less than 2 (but see the text for exceptions).
Disk (Logical or Physical)\ % Disk Time	As low as possible.
Disk (Logical or Physical)\ Queue Length	Less than 2.
Disk (Logical or Physical)\ Avg. Disk Bytes/Transfer	As high as possible.
Internet Information Service Global\ Cache Hits %	As high as possible.
Web Service\ Bytes Total/sec	As high as possible.
Active Server Pages\ Request Wait Time	As low as possible.
Active Server Pages\ Requests Queued	Zero.
Active Server Pages\ Transactions/sec	As high as possible.

In addition to these, you will find the Computername\ System\ Threads, Computername\ System\ Processes, Computername\ System\ Context Switches/sec and other System Object counters useful for monitoring your server’s use of System resources.