Intresting articles on queue depth

While doing some research on understanding Queue depth from an Oracle database running on AIX perspective, I came across these two articles which have done an excellent job explaining it.

http://dsstos.blogspot.com/2008/12/hostlun-queue-depths-command-taq.html

http://www-01.ibm.com/support/docview.wss?uid=tss1td105745

http://www-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/TD105745