I ran perf monitor and saw the number for PhysicalDisk:Avg Disk Queue Length is 2.93 during an one (1) hour period (interval is 15 seconds). This is for drive D on a 4 disk RAID5. Does this mean I have to divide 2.93 by 4 (number of disks) in order to have an accurate number for Avg Disk Queue Length? I saw a video training saying so but I am still not sure.
Look at Avg Disk sec/Read and Avg Disk sec/Write instead for latency, and look at Disk Read Bytes/sec and Disk Write Bytes/sec for throughput. Queue length is interesting, but if you're getting very low latency and very high throughput compared to your best case scenario, I would ignore it. In my SQLIO testing, I've noted that very low outstanding IOs tend to get lower performance out of arrays, whether local or on SANs.
wmic /namespace:\\root\cimv2 path Win32_PerfFormattedData_PerfDisk_LogicalDisk get /all
wmic /node:"server" /namespace:\\root\cimv2 path Win32_PerfFormattedData_PerfDisk_LogicalDisk get /all
will get you some information, but, unfortunately, not the critical Avg Disk sec/Read and Avg Disk Sec/Write, because Microsoft decided to round what should be tiny fractions of a second to a full Integer, rendering those fields worthless.
I have yet to find direct information on getting those measurements from
wmic /namespace:\\root\cimv2 path Win32_PerfRawData_PerfDisk_LogicalDisk get /all
but for manual monitoring, Perfmon translates things just fine.