IBM eX5 Implementation Guide

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.

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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