Dell OpenManage Power Center’s Power Policies for 12th-Generation Servers This Dell white paper describes the advantages of using the Dell OpenManage Power Center to set power policies in a data center.
Dell Power Center’s Power Policies for 12th-Generation Servers This document is for informational purposes only and may contain typographical errors and technical inaccuracies. The content is provided as is, without express or implied warranties of any kind. © 2012 Dell Inc. All rights reserved. Dell and its affiliates cannot be responsible for errors or omissions in typography or photography. Dell, the Dell logo, and PowerEdge are trademarks of Dell Inc.
Dell Power Center’s Power Policies for 12th-Generation Servers Contents Executive Summary .................................................................................................... 5 Introduction ............................................................................................................. 5 Dell 12th-Generation Servers Employ Intel Node Manager for Power Monitoring and Management ..... 5 Power Capping Based on Real-Time Power Measurement ...........................................
Dell Power Center’s Power Policies for 12th-Generation Servers Figure 10. Maximum power consumption spikes above the capping value ..................................
Dell Power Center’s Power Policies for 12th-Generation Servers Executive Summary Dell OpenManage Power Center uses Intel Node Manager for real-time power monitoring and management on Dell 12th-generation servers. IT administrators can set power capping values for individual servers as well as for groups of servers in order to manage power consumption within their environment.
Dell Power Center’s Power Policies for 12th-Generation Servers Setting an Efficient Capping Value It is important to set an efficient power cap value for each server. While setting the value too high is inefficient, setting the cap value too low will impact performance and prevent the server from carrying out its computational workload effectively. Having the real-time power usage data from Power Center is a good starting point for setting an efficient capping value on the server.
Dell Power Center’s Power Policies for 12th-Generation Servers Figure 1. Power operation range and capping value Power supply maximum or face plate: 500W Upper bound power: 350W Capping value: 280W Maximum power consumption: 220W Average power consumption: 200W Lower bound power: 100W Figure 2.
Dell Power Center’s Power Policies for 12th-Generation Servers Power Capping a Group of Servers Power Center can Aggregate the Data and Set the Power Capping at any Group Level Power Center can aggregate power data from servers to provide power monitoring and capping at any group level. It provides both static and dynamic capping for a rack, aisle, room, an entire data center, or any logical group.
Dell Power Center’s Power Policies for 12th-Generation Servers Figure 4. Static capping in Power Center Group capping value Capping value for each server Dynamic Capping Due to changes in workload(s), the power demand of each individual server can vary greatly and static capping on an individual server basis may not be the best policy as it does not allow a server’s power allocation to grow where power is available, resulting in artificial restriction of the system’s performance.
Dell Power Center’s Power Policies for 12th-Generation Servers servers; however, once excess power is available (known as headroom), the allocation of that power is distributed considering priority. Let’s look at an example: Group G1 with 3 servers: S1, S2 and S3, and the group capping is set at 2000W. S1 is set at high priority, while S2 and S3 are set at medium priority. The table below demonstrates how the power capping is adjusted after each sampling interval (T1, T2, etc.).
Dell Power Center’s Power Policies for 12th-Generation Servers The power is dynamically adjusted among servers in a group 3500 3000 S1 2500 2000 S2 1500 S3 1000 Total 500 Capping 0 T1 T2 T3 T4 How to Set Power Policies using Power Center The administrator has the option to create multiple capping values and apply different capping values on the server at different times to optimize the use of power resources in the data center.
Dell Power Center’s Power Policies for 12th-Generation Servers Figure 5.
Dell Power Center’s Power Policies for 12th-Generation Servers Figure 6. Setting group capping value in static policy Group capping value Capping value for each server Setting Dynamic Policies Figure 7 illustrates that when setting the dynamic policy, the user is asked to set the priority for each server, which is different from the static policy, where the user is asked to set the cap value for each server.
Dell Power Center’s Power Policies for 12th-Generation Servers Figure 7. Setting priorities in dynamic policy The power cap is dynamically distributed based on the priority The main purpose of a dynamic policy is to maintain the group budget and to balance the power resources to optimize the performance of the servers in the group, based on recent measurements of power consumption.
Dell Power Center’s Power Policies for 12th-Generation Servers Managing Power Policies Power Center provides the aggregated data for power monitoring at the group, rack, row, or room level, or an entire data center. Based on the group hierarchy and power monitoring, users can set the appropriate power policy for each group. However, if there are many groups and the hierarchy becomes overly complex, it would be difficult to track and manage the power policy for each group.
Dell Power Center’s Power Policies for 12th-Generation Servers Hence, power over-provisioning is a common issue in power management when using the nameplate instead of the actual measured power usage values. It is also one of the best and easier ways to first address power utilization in the data center. Consider the following example: A server has a nameplate capacity at 500W and a total rack capacity of 5000W, allowing the administrator to deploy 10 servers.
Dell Power Center’s Power Policies for 12th-Generation Servers minimize the power usage of all the servers in a rack. From the Power Center user interface, the user navigates to the physical-based group of that rack in Power Center and then applies the EPR feature to it. Note that EPR is not meant to be used for long periods of time and certain Power Center configuration features may be disabled during the application of EPR. Figure 9 shows a rack under EPR.
Dell Power Center’s Power Policies for 12th-Generation Servers Peak Power Reporting and Power Capping Power Center measures and reports the power consumption data, including the minimum, maximum and average power consumption of servers, and presents them on graphs at each sampling period; for example, every 15 minutes, 1 hour, etc. In Figure 10, maximum power consumption (pink line in the graph) is at one point above the power capping value (yellow straight line in the graph).
Dell Power Center’s Power Policies for 12th-Generation Servers Using iDRAC in Conjunction with Power Center Dell iDRAC7 Enterprise is also a tool for monitoring and setting the power capping for an individual server. If both Power Center and iDRAC are used for setting the power cap, there is the potential for a power capping conflict. Because the same power policy identifier is used between Power Center and the iDRAC, Node Manager will simply enforce the last capping value sent to it.
