Disk queue length on Mac OSX

Question

On Linux, disk queue length can be calculated by analyzing the sources of iostat. It has column avgqu-sz which is the queue size - http://www.cyberciti.biz/tips/linux-disk-performance-monitoring-howto.html

However on Mac OSX I don't find anything similar to this. The closest counters it has are nanoseconds of read and write latency, however I don't see how to obtain disk queue length from them (and all the counters OSX exposes - https://developer.apple.com/library/mac/#documentation/Kernel/Reference/IOBlockStorageDriver_header_reference/Reference/reference.html)

Answer 1

The dtrace script iopending samples disk queue length and displays a histogram.