| 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. |