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Best practice for blade power settings

Trusted Contributor

Best practice for blade power settings

Scott needed some advice on server power setting best practices:




I am looking to understand the choice of OS control over Dynamic and why particularly in Windows?


I am of the opinion that they both do basically the same thing but OS control requires additional driver (and overhead) to enable. So if all things are equal why add the additional touch points and overhead? What am I missing?




from Mark:




Some people (me included) prefer OS Control Mode.


Best Practice on our high end servers is OS Control Mode for Windows, and probably now for Linux (there was a bug with c state transitions in Linux many years ago and people shy away from OS control mode due to that bug, just to be conservative, but it is fixed).


I’m not a blade person, but that said I recently visited a customer that had got upset with a CE changing their blade config from OS Control Mode to High Performance (and it was a Linux house) that then messed up his power saving config.


Not sure what OS you’re using, but if W2K8R2 or Linux RHEL >5.4 OS Control Mode would be my suggestion. You’ll still get power savings but when you need all the CPU you’ll get that too.


For Windows “OS Control Mode” does not need an additional driver – I cannot confirm that for Linux as I do not know Linux well, but suspect not too. All this does is allow the OS to control C States of the processor. I can’t think of any place better for that to occur, as the OS knows its workload.


As for the HP Dynamic * list. The default of balanced is just absolutely terrible for most situations. You just cannot get any performance out of it – it may give you better power savings, but TPCC and VMark for any server in the ISS / BCS product line with it are not good. As for OS Control Mode v HP High Performance there is no difference in bench marks but there is in power savings (OS Control Mode gives better savings).


Your choice!




From Chris:




Does VMware ESXi have the capability to effectively use OS Control mode?

Which option is recommended for VMware ESXi 4 and 5?




Sam replied:




See page 5 of the attached document. The recommendation is OS Control if DRS is in use.




Here is the document referenced. Any other comments or experiences ont his subject?