Disk I/O Issues (Dell PERC)

[dhaddad1]

I have the following VM Host:

Dell R710

PERC6/I, RAID 10, 146GB 10k SAS

CPU 2x L5520 @ 2.27

RAM: 16.00 GB

Running the dell esxi-5.5.1331820 build of esxi

With no other running vms on the host, doing a IO drive test returns the following results:

65% random read write 8K

Total I/O - 1852

Total MBps - 15

Average Response: 28

Max Response: 369

These seem very strange? The firmware is current on the controller, and write-back is enabled on the array. Thoughts?

[JPM300]

That does seem a little low.  I know some of the raid controllers has options in the write back cache as to what you want it to prioritize on.  For instance you can set it to 50read/50write, or 20/80 ect.  See if there is any other options in your raid controller write back cache options.

Also run the same IO test with 4K blocks and see what your results are.

[dhaddad1]

There are no such options in the PERC controllers. With 4K IOPS: 1410, MBs 5.78, Average IO 133ms Max IO 2810ms CPU: 62%

This is testing from a guest OS

[JPM300]

How many disks are in the RAID10 just 4 right?

The IOPS kinda seem like they are where they should be but the MB/s seems low.  I would call dells server support up and ask them what the metrics are supposed to be or find the white papers on that particular raid controller.  It could be its working as intended??