Transcript of Dell 10G Eval Wiki Web Chat of 1/8/08 (edited for brevity, clarity and accuracy)

DELL-davej I'd like to welcome everyone to the 4th Dell 10G Blades Eval Wiki Web Chat
DELL-davej There are 3 things I wish to cover about Power Management on the 10G Blades: Power Supply redundancy, Dynamic Power Supply Engagement and Server Power Throttling
DELL-davej The best source I've found so far is the CMC document (CMC Users Guide Draft.pdf) available from the Eval FTP site (customers need to ask their account teams to get them it)
DELL-davej Let's talk about Power Supply redundancy. Production M1000e blade chassis will ship with either 3 or 6 power supply units (PSUs). With 6 you get full AC redundancy.
DELL-davej That is, you should connect 3 PSUs to one AC grid in your data center and the other 3 PSUs to a second grid. So if you lose one grid you still have enough power to run your blades
DELL-davej With 3 PSUs you get DC redundancy. If one should fail you can still run off of two
DELL-davej In fact you can set a mode called Dynamic Power Supply Engagement, that will put one of the 3 PSUs in Standby if not needed
DELL-davej If you have all 6 PSUs Dynamic Power Supply Engagement can put 2 PSUs in Standby
DELL-davej You also have the ability to define power thresholds. The idea behind the threshold is, if you have limited power in your data center, you can control the amount that your blades draw
DELL-Todd_Muirhead How much power can be saved by putting 2 of the 6 in standby mode?
DELL-davej That's a good question because the PSUs themselves are very efficient.
DELL-davej Let me give you some numbers: at idle I am seeing each of the four blades draw about 150W, and the entire chassis is drawing 900W
DELL-davej So the chassis, including PSUs, CMC, iKVM and IOMs is only drawing 300W total
DELL-davej The CMC has some powerful algorithms to monitor power consumption by all the blades and limit power to individual blades in a prioritized fashion if there is not enough power available
DELL-davej I was going to try to play with that by setting an artifically low threshold but the lowest I can go is 2100W (this is hardcoded)
DELL-davej The blades draw about 200W at 80% utilzation so I can't drive the 4-blade chassis above about 1100W
DELL-davej So we'll leave that as an exercise for the interested student!
DELL-davej BTW the term used for the CMC limiting the power to a blade is what I mentioned earlier, Server Power Throttling
DELL-davej All of this is controlled through the CMC (using either the GUI or racadm CLI) but you have to go into the individual blade iDRACs to see how much power they are consuming
DELL-ScottH How does the power limiting to the blades work ? Does it not power up the blade, or does it have a way of throttling the CPU and such ?
DELL-davej It definitely will prevent a blade from powering up if there is insufficent power but it also will decrease power to a blade dynamically if necessary
DELL-davej The iDRAC detects the lower power and ratchets down the CPU speed
DELL-davej The blades start off with a power budget (310W for the Intel systems with 2 quadcore chips and 297W for the AMD blades with 2 dualcore chips)
DELL-davej So their budgets could be throttled quite a bit before affecting performance
DELL-davej I think those power budget values are calculated based on blade components. I haven't found a place to set them.
DELL-davej There's some nice power stuff in the iDRAC (again, accessible through the GUI or racadm). There is total KWH consumed, and peak power and amperage. All can be reset with a button click
DELL-RogerF Can you set preferences or priorities on which blades if any get throttled back first?
DELL-davej Yes
DELL-Todd_Muirhead Can the power consumed be viewed in IT Assistant console?
DELL-ScottH There's a power monitoring task in the new ITA 8.1 (with OM 5.3) , lets you set thresholds and limits and sends alerts ...
DELL-ScottH but the new tab for "Performance and Power" in the Devices interface doesn't show up on our blade system.
DELL-ScottH Need to get the MLK systems in and see what shows up for power
DELL-davej I forgot to mention that each PSU can provide 2360W. So 3 PSUs should be able to easily handle 16 blades
DELL-RogerF Are there any options for dynamic throttling preferences i.e. low CPU utilization blades first?
DELL-davej No. You can only designate a number from 1 to 10 (1 being highest priority). It will start throttling the lowest priority first. In the case of a tie it will do the lower blade position first.