I'd like to check to see if the way I've started to collate data on our VMs is valid and therefore worth perusing.
Using powercli I'm pulling back 5 min data of all VMs in our environment, The script runs at the end of the day and pulls back various metrics (cpu.usage.average, cpu.ready, mem.active.average..etc). They are then processed and I produce a day summary of each VM which I can then aggregate into weekly, monthly etc. As I have 5 minute data I'm able to see the finer peaks and troughs that might be missed if the longer periods were used.
An example of a days data is attached
B - Num CPU assigned
C - Average CPU usage for day,
D - Num of CPU user can be resized to (Cpu * Avg)/100,
E - New potential CPU size of VM (column D rounded up)
F - Max CPU used
G - Num of CPU VM can be resized to based on days Max
H - New Potential CPU size of VM based on days Max (column G rounded up)
Second table row shows the SUM of the column.
Question1
Now, is it valid for me to take the sum from column H (or perhaps column E) and use that to size a host. So, based on 47, I would need a 48 (rounded up) processor (inc hyperthreading) host if I wanted to move these VMs onto another host. (leaving aside overhead).
Question2
The VMs are oversized in the memory department too. If they were reduced, would there be any effect at all on CPU if Ram were reduced?
Question3
Anything obvious I'm missing or should be including?
Appreciate feedback. Apologies if i've not been clear, feel free to ask for clarification.