38 IBM eX5 Implementation Guide
Figure 2-18 UEFI System Settings panel
For more information about system-specific UEFI options, see the following sections:
򐂰 IBM System x3850 X5: 6.9, “UEFI settings” on page 259
򐂰 IBM System x3690 X5: 7.8, “UEFI settings” on page 337
򐂰 IBM BladeCenter HX5: 8.5, “UEFI settings” on page 396
2.7.1 System power operating modes
IBM eX5 servers are designed to provide optimal performance with reasonable power
consumption, which depends on the operating frequency and voltage of the processors and
memory subsystem. The operating frequency and voltage of the processors and memory
subsystem affect the system fan speed that adjusts to the current cooling requirement of the
server.
In most operating conditions, the default settings are ideal to provide the best performance
possible without wasting energy during off-peak usage. However, for certain workloads, it
might be appropriate to change these settings to meet specific power to performance
requirements.
The UEFI provides several predefined setups for commonly desired operation conditions.
This section describes the conditions for which these setups can be configured.
These predefined values are referred to as
operating modes and are similar across the entire
line of eX5 servers. Access the menu in UEFI by selecting System Settings Operating
Modes Choose Operating Mode. You see the four operating modes from which to
choose, as shown in Figure 2-19 on page 39. When a mode is chosen, the affected settings
change to the shown predetermined values.
We describe these modes in the following sections.
Chapter 2. IBM eX5 technology 39
Figure 2-19 Operating modes in UEFI
Acoustic Mode
Figure 2-20 shows the Acoustic Mode predetermined values. They emphasize power-saving
server operation for generating less heat and noise. In turn, the system is able to lower the fan
speed of the power supplies and the blowers by setting the processors, QPI link, and memory
subsystem to a lower working frequency. Acoustic Mode provides lower system acoustics,
less heat, and the lowest power consumption at the expense of performance.
Figure 2-20 Acoustic Mode predetermined values
Efficiency Mode
Figure 2-21 on page 40 shows the Efficiency Mode predetermined values. This operating
mode provides the best balance between server performance and power consumption. In
short, Efficiency Mode gives the highest performance per watt ratio.
40 IBM eX5 Implementation Guide
Figure 2-21 Efficiency Mode predetermined values
Performance Mode
Figure 2-22 shows the Performance Mode predetermined values. The server is set to use the
maximum performance limits within UEFI. These values include turning off several power
management features of the processor to provide the maximum performance from the
processors and memory subsystem. Performance Mode provides the best system
performance at the expense of power efficiency.
Figure 2-22 Performance Mode predetermined values
Performance Mode is also a good choice when the server runs virtualization workloads.
Servers that are used as physical hosts in virtualization clusters often have similar power
consumption management at the operating system level. In this environment, the operating
system makes decisions about moving and balancing virtual servers across an array of
physical host servers. Each virtualized guest operating system reports to a single cluster
controller about the resources usage and demand on that physical server. The cluster
Chapter 2. IBM eX5 technology 41
controller makes decisions to move virtual servers between physical hosts to cater to each
guest OS resource requirement and, when possible, shuts down unneeded physical hosts to
save power.
Aggressive power management at the hardware level can interfere with the OS-level power
management, resulting in a common occurrence where virtual servers move back and forth
across the same set of physical host servers. This situation results in an inefficient
virtualization environment that responds slowly and consumes more power than necessary.
Running the server in Performance Mode prevents this occurrence, in most cases.
Custom Mode
The default value that is set in new eX5 systems is Custom Mode, as shown in Figure 2-23. It
is the recommended factory default setting. The values are set to provide optimal
performance with reasonable power consumption. However, this mode allows the user to
individually set the power-related and performance-related options.
See 2.7.3, “Performance-related individual system settings” on page 43 for a description of
individual settings.
Figure 2-23 Custom Mode factory default values
Table 2-5 shows comparisons of the available operating modes of IBM eX5 servers. Using the
Custom Mode, it is possible to run the system using properties that are in-between the
predetermined operating modes.
Table 2-5 Operating modes comparison
Settings Efficiency Acoustics Performance Custom (Default)
Memory Speed Power Efficiency Minimal Power Max Performance Max Performance
CKE Low Power Enabled Enabled Disabled Disable
Proc Performance States Enabled Enabled Enabled Enable
C1 Enhanced Mode Enabled Enabled Disabled Enable
CPU C-States Enabled Enabled Disabled Enable

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