VNX Analyser - Lun IOPS

In VNX Analyser, when I look at Write Throughput of a LUN, am I seeing "application write I/O" or "back-end wite I/O?"

--In Analyzer, the Throughput numbers for a LUN always refer to the front-end IO being sent to the LUN from the Host/Application.

We are have a production host that is being replaced. The new host has its LUNs carved out on a few storage pools. I'm trying to forecast whether the existing storage pools will support the anticipated production load by adding up the throughput not handled by FAST cache on the current production LUNs to the throughput not handled by FAST cache on the storage pool.

Can I go by the raw numbers, of do I need to figure in a RAID penalty?

-- RAID penalty will always come into picture, whether it is a storage pool or a RG, since the pools themselves are made up of private RGs internally. You will have to make sure that you understand the internal structure of a pool when you do your IOPS calculation.

In other words, when I see a LUNs read, write or total throughput in VNX Analyser am I seeing the I/O load post-RAID penalty??

-- Again, the throughput numbers seen in the Analyzer are the numbers for the IO received from the host side. This doesn't take RAID penalty into consideration. For that, please check the IO on the backend disks which are a part of the RG or Storage Pool from which the LUN has been carved.

Thank you.

The Ask the Expert: Performance Calculations on Clariion/VNX thread sheds some light on this, as well.

You mean write penalty, right? RAID penalty sounds like somebody is trying to kick a DAE into a goal on a soccer field.

I like that discussion a lot! It explains a lot of how write penalties shoud be calculated!!