это написано в том гайде, на который я дал ссылку - это соотношение двух величин
Avg. Disk Queue Length (Avg. Disks Read Queue Length, Avg. Disk Write Queue Length)
Avg. Disk Queue Length is equal to the (Disk Transfers/sec) *( Disk sec/Transfer). This is based on “Little’s Law” from the mathematical theory of queues. It is important to note this is a derived value and not a direct measurement, I recommend reading this article from Mark Friedman, the information still applies to Windows 2008 R2.
As you would expect, the Avg. Disk Read Queue Length is equal to the “(Disk Reads/sec) * (Disk sec/Read)” and Avg. Disk Write Queue Length is equal to the “(Disk Writes/sec) * (Disk sec/Write)”.
http://en.wikipedia.org/wiki/Little%27s_lawhttp://www.oreillynet.com/pub/a/network/2002/01/18/diskperf.html