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trip. HP has tested Dynamic Power Capping to ensure that it can prevent tripping circuit breakers that have a 
specified trip time of 3 seconds or longer at 50 degrees C and 150 percent overload. 
Dynamic Power Capping can keep server power consumption below the power cap in real time. Therefore, 
administrators can use it as an effective tool in planning and managing both electrical provisioning and cooling 

requirements in the data center. An administrator can electrically provision a PDU or a rack to something less than 
the full faceplate power rating of all the servers supported because Dynamic Power Capping will prevent a sudden 
power demand from exceeding the power cap and tripping a circuit breaker. 

Support for Power Capping in ProLiant servers 

ProLiant servers with power measurement circuitry support basic Power Capping:  

 

ProLiant G5 servers ML350, ML370, DL360, DL365, DL380, and DL385  

 

All c-Class BladeSystem servers 

Basic Power Capping requires the following system firmware: 

 

iLO 2 version 1.30 or later 

 

System BIOS 2007.05.01 or later 

Support for Dynamic Power Capping requires a certain level of ProLiant hardware, as well upgrades to the 

following system firmware: 

 

System BIOS 2008.11.01 or later 

 

iLO 2 version 1.70 or later 

 

Onboard Administrator firmware version 2.32 or later (for HP BladeSystem enclosures) 

At introduction, support for Dynamic Power Capping is available on a limited set of ProLiant servers and a larger set 

of ProLiant c-Class server blades. Many ProLiant G5 servers can support Dynamic Power Capping if they have fully 
qualified BIOS and iLO firmware. Please consult the most recent 

support matrix

.  

Group power capping for servers through Insight Control 

One of the most powerful uses of power capping is monitoring and controlling the power use of an entire group of 

servers. This capability is available through Insight Control. Administrators can apply a group power cap to any 
group of servers that they can select within Insight Control, including Insight collections. 
Insight Control displays the aggregated minimum and maximum power consumption for an entire group of servers 

and their aggregated power supply rating. Each of these numbers is simply the sum of the respective values for the 
individual servers in the group. Using the Insight Control interface, an administrator can apply to the server group a 
power cap that is between the minimum power and the power supply rating of the entire group.  
Insight Control assigns an individual power cap to each server in the group. It is a proportional allocation of the 
group power cap. The total of the individual power caps equals the group cap. The individual power caps for the 

servers continue until an administrator changes them through the iLO or Insight Control interface. 
Figure 3 shows a group consisting of four servers. The left side of the figure shows the measured minimum and 
maximum power consumption for each server. The right side of the figure shows that the aggregated maximum 

power consumption for this group is 1375 watts. The aggregated minimum allowable power consumption is 725 
watts. In this example, an administrator has applied a power cap of 1115 watts to the group. This group cap limits 

the group power consumption to 60 percent of the wattage between the aggregated minimum and maximum. To 
implement this group power cap, Insight Control applies to each server a power cap that is 60 percent of the 
wattage between that server’s minimum and maximum power consumption. This results in individual power caps of 

320, 170, 305, and 320 watts respectively. 

Summary of Contents for Integrity NonStop NB54000c

Page 1: ...0 Setting power caps for servers 10 Setting a power cap for a single server 11 Setting a power cap for a group of servers 13 Setting a BladeSystem enclosure power cap 13 Setting a power cap for a group of enclosures 14 Using power capping in data center provisioning 15 Choosing effective power caps 15 Power capping to peak power consumption 17 Power capping to average power consumption 19 Using En...

Page 2: ...Providing a guardband for a power capping group 23 Summary 24 For more information 25 Call to action 25 ...

Page 3: ...a given computational workload Power capping simply limits the amount of power that a server can use at any point in time This lets you allocate data center power and cooling resources more efficiently In general if a given power cap restricts the amount of power that a server would normally use to perform a task that task will take longer Over time the server will consume about the same total ene...

Page 4: ...throttling Clock throttling is another method for lowering processor power consumption Depending on the processor model the system BIOS can either reprogram the processor to run at a lower frequency or modulate the processor between running periods and stopped periods Both methods have the same net effect of lowering the processor s overall power consumption below the levels available using P stat...

Page 5: ...s and even the mix of instructions executed As long as the power consumption remains below the power cap the power capping control mechanism takes no action and there is no affect on server performance Minimum and maximum power consumption for a server The power management system in each server determines both the minimum and maximum power consumption for the server It determines these two values ...

Page 6: ...Capping as basic Power Capping throughout the remainder of this paper Table 3 Characteristics of Dynamic Power Capping and basic Power Capping Dynamic Power Capping Basic Power Capping Power capping executed from Power management microcontroller iLO and system ROM BIOS Control of processor power Direct hardware connection to processor to control P state clock throttling at the processor hardware l...

Page 7: ...ht Control One of the most powerful uses of power capping is monitoring and controlling the power use of an entire group of servers This capability is available through Insight Control Administrators can apply a group power cap to any group of servers that they can select within Insight Control including Insight collections Insight Control displays the aggregated minimum and maximum power consumpt...

Page 8: ...etting a power cap for the enclosure indirectly creates power caps for the server blades within it The Onboard Administrator OA then actively manages these power caps and reallocates power as workloads change over time Elements of an enclosure power cap With Enclosure Dynamic Power Capping an administrator sets a power cap for an entire BladeSystem enclosure not simply for the server blades in the...

Page 9: ... The OA maintains the overall enclosure cap by monitoring and managing the power consumption of the server blades To accomplish this the OA collects the overall enclosure power use and the total power used by the managed server blades From this data the OA constructs a blade power budget representing the amount of power that the blades can consume while keeping the overall enclosure power consumpt...

Page 10: ...er their caps within the 3 seconds required for normal circuit breaker protection However the redundant side of the enclosure power can absorb the transient overage until overall power consumption is again under the enclosure cap If N N power redundancy fails then a hardware based failsafe mechanism overrides the Enclosure Dynamic Power Capping and immediately lowers all server blade processors to...

Page 11: ...through Insight Control In the iLO 2 browser based interface Figure 5 Power Capping Settings is located beneath the Power Management tab in the Settings subsection The iLO 2 Power Management Settings screen indicates whether the server supports Dynamic Power Capping Figure 5 Setting a power cap for an HP BladeSystem server using iLO 2 ...

Page 12: ... Insight Control Power Capping is located beneath the HP Power Management Actions section of the interface as shown in Figure 6 Figure 6 Setting a power cap for an HP BladeSystem server using Insight Control ...

Page 13: ...and the power supply rating of the entire group Figure 7 Setting a group power cap in Insight Control Setting a BladeSystem enclosure power cap You can use either the OA or Insight Control to set the power cap for a BladeSystem enclosure to any value between the power cap lower bound and the maximum available power for the enclosure Figure 8 shows the Power Management screen from HP Onboard Admini...

Page 14: ...The lower bound of the power cap is 15499 watts It is higher than the maximum power measurement because it represents the lowest reasonable power cap for the group that is sustainable under all operating conditions Applying a power cap value of 25 000 watts to the group causes Insight Control and the OAs to create and apply a separate Enclosure Dynamic Power Cap to each of the five enclosures usin...

Page 15: ...apping takes this one step further Its ability to control server power consumption in real time allows administrators to use power capping for planning and managing both their electrical provisioning and their cooling infrastructure Choosing effective power caps Setting an effective power cap involves determining the lowest value for the power cap that will still meet the power requirements for a ...

Page 16: ...d use under environmental and load conditions It is one of the numbers that an administrator could use when calculating the maximum power and cooling requirements to support this system in the data center For a rack containing a group of eight of these servers the total requirements would be 3384 watts Figure 10 HP Power Calculator results for a configured ProLiant DL380 G5 server ...

Page 17: ... the history of peak and average power consumption for the group provides a good starting point for deciding how to set effective power caps that meet different power management objectives in the data center Power capping to peak power consumption As the power consumption graph in Figure 11 shows peak power consumption for the eight server group running this workload is consistently about 3116 wat...

Page 18: ...r Capping applied the same circuit can support over 10 more servers if all 10 have the same power cap as the first eight servers Table 5 Power provisioning for eight DL380 G5 servers when capping to peak power consumption using Dynamic Power Capping Description Power Traditional input power provisioning for 8 DL380 G5 servers 1217 input VA at 208 volts de rated by 20 percent 7760 watts 970 x 8 Max...

Page 19: ...o average 1900 watts Guardband 190 watts Savings in power capacity 1294 watts Additional servers that can be provisioned within the same cooling infrastructure 5 Dynamic Power Capping will more significantly affect any workload transients exceeding the cap Therefore HP recommends capping a server group supporting Dynamic Power Capping at the average power consumption only in applications where pea...

Page 20: ...of servers using Insight Control and power capping This will quickly lower server power consumption and heat generation in the affected area until you can restore cooling Under these circumstances it may be appropriate to set power caps significantly lower even though they may affect performance Using HP SIM you can define and store groups of servers as collections This allows you to apply power c...

Page 21: ...u access this scheduling capability using the Configure Power Management Power Usage Controls menu Task scheduling consists of several steps including defining the new power cap Figure 13 and creating the schedule for applying the power cap Figure 14 Figure 13 Setting a power cap as part of a scheduled task Figure 14 Defining the scheduled Insight Control task in Systems Insight Manager Constructi...

Page 22: ...ng the steady state power consumption of servers in real time However it does not control the power consumption of servers at start up when their maximum power consumption is measured If a group of servers on the same PDU power up simultaneously there will be a window during start up before Dynamic Power Capping is active During that window the servers will draw close to their maximum power at rou...

Page 23: ...or manages server power use as long as a server s power consumption remains below the power cap setting Power capping will override Power Regulator only if power consumption exceeds the established power cap Power capping and CPU utilization Both power capping and Power Regulator involve manipulating the system processor at a very basic level As a result power capping can affect the processor util...

Page 24: ...to make significant hardware or environmental changes for one or more servers should increase guardband to the group total to allow for the changes However best practice is to re evaluate the server caps after adding hardware and to select caps that are at least halfway between the minimum and maximum power consumption for a server or server group When you follow best practices additional guardban...

Page 25: ...ogy brief http h20000 www2 hp com bc docs support SupportManual c00300430 c00300 430 pdf Power Regulator http h18013 www1 hp com products servers management ilo power regulator html Call to action Send comments about this paper to TechCom HP com Copyright 2008 2009 2010 Hewlett Packard Development Company L P The information contained herein is subject to change without notice The only warranties ...

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