Power Management on Blades?

[chuckk281]

John has a power management question:

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My customer is working on a project to reduce energy costs and is considering shutting down Blade servers when not in use (mainly in a Citrix farm, reduce the amount of servers users can logon to) but I’m steering him away from this and have given him information on Power capping and Insight Control power management etc.

He’s asking if HP have any collateral on why it’s not good practise to continually poweroff/poweron servers.

Any feedback would be appreciated as always.

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Reply from David:

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Not so much.  It really isn’t an official HP recommendation but customer/field folklore based on past experiences when servers haven’t rebooted.  This isn’t always because of the hardware; it just as likely is due to corrupt file systems, incomplete patches/upgrades that wouldn’t init on reboot, SAN boot storms and the like.

You’re on the right track…make sure that he has the latest Platinum Plus Power Supplies (that achieve high efficiencies even at low power consumption, which can effectively halve the power draw in idle states), utilize Dynamic Power Saver on the power supplies to idle ones not needed, power capping and more.  This will likely have more positive impact than turning off servers, and has the added benefit of the resources being able to respond if demand were to remain high during normal idle hours (accounting department burning the midnight oil to close out a quarter, etc).

The last thing I’ll leave you with is a customer comment from when I did I research project on a precursor to our current power management products.  The customer said, “I don’t buy servers to turn them off…”  By which ominous comment the customer was trying to say, be careful what you propose to us because if we discover that we don’t need all the servers we’re buying, there will be repercussions…

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And some info from Michael;

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     I wonder what % of max power Gen8 servers consume when idle? A while back I think servers ran at around 50% when idle. As a result lots of organisations researched powering down idle servers and there are quite a few papers out there.

FYI:-

. Citrix’s approach http://support.citrix.com/proddocs/topic/xenapp6-w2k8/ps-power-capacity-mgt-wrapper-v1.html

. VMware (i) reduce power consumption of the hosts by letting ESX control the power states and then (ii) use VMware DPM to migrate VM’s off hosts with low utilisation and power down the hosts.

Some papers that may be of use:-

. Risk of power down http://www.infoworld.com/d/green-it/powering-down-servers-calculated-risk-868

. HP Labs https://twiki.hpl.hp.com/pub/SIEL/ResultsPublications/IdleMachinePowerSavings_v24_noCopyright.pdf

. http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00300430/c00300430.pdf

. http://www.vmware.com/pdf/Perf_Best_Practices_vSphere5.0.pdf

. http://h20000.www2.hp.com/bc/docs/support/SupportManual/c03161908/c03161908.pdf

It would be interesting to know if many folks are doing this – for datacentres as opposed to desktops that is.

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Any comments or questions?