Perfmon stats on existing RAID for SAN planning

[netwrkmgr]

We are in the process of virtualizing our Windows servers and have been using PerfMon to obtain current disk I/O stats. The goal is to build the appropriate arrays on the SAN which would best suit the workload.  Currently, all of the physical servers have a local RAID5 array. The servers also have BBW cache.   Example Physical  Server Stat: (Other servers are higher)  (8 hours) Average Read/Sec: 12.77 Average Write/Sec: 4.9 Avg Write Queue Length: .012 Avg Read Queue Length: .001  So, how would we interpret the results of PerfMon running against a current RAID5 set to help us in our planning? Would we need to "uncalculate" the current RAID penalty to get raw potential I/O of the server / applications?   Many thanks in advance for any assistance.

[mcowger]

Perfmon stats are collected at the 'frontend', meaning they dont include any of the RAID penaltys (nor the value of array caching, etc)

They are a reasonable thing to give to your array vendor to determine what you need (let the array vendor calculate RAID penalties, etc - there are array specific subleties that matter).

Also, most vendors (including us, EMC) will want 24 hrs (at least) wirth of data so we can see the peaks, etc.  A simple average isn't good enough.