7
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.
