Avg. Disk Sec/IO Not a Physical Disk Counter

• Microsoft Windows NT Advanced Server version 3.1

SUMMARY

The term "Avg. Disk sec/IO" is incorrectly used in the Windows NT Advanced Server "Concepts and Planning Guide." On page 194 of the guide under the heading of "Checking for Excessive Paging," the phrase "Avg. Disk sec/IO" is referred to as a counter for the physical disk in Performance Monitor. No such counter exists under the heading physical disk in Performance Monitor.

MORE INFORMATION

The phrase "Avg. Disk sec/IO" is being used interchangeably with the actual counter label of "Avg. Disk sec/Transfer" On page 550 of the Windows NT Advanced Server "System Guide," this is explained. "Avg. Disk sec/IO" is defined there in terms of average disk-transfer times exactly as "Avg. Disk sec/Transfer" is defined with the "Explain" button in the Add To Chart dialog box of the Performance Monitor. The counter "Avg. Disk sec/IO" does not exist, it just takes the form of "Avg. Disk sec/Transfer."

Also the formula to use for finding excessive paging is vaguely referenced with the phrase: "To confirm excessive paging, add together the Avg. Disk sec/IO (a physical disk counter) and Pages/sec counter values." The correct method is to add "Avg. Disk sec/Read" and "Avg. Disk sec/Write" to get the number for "Avg. Disk sec/IO (or Transfer)."