ISS Technology Update
When to disable processor cores
While disabling cores may seem counterintuitive to delivering higher performance, there are at least three situations in which
disabling processor cores can prove beneficial.
Reducing power use. Disabling processor cores reduces processor power use. If a server is being used in an application
environment that does not depend heavily on multi-threading, disabling cores can lower power consumption without
materially affecting performance.
Increasing overall performance. Some applications benefit from higher core frequency rather than from additional processing
cores. When Turbo Mode is enabled for Intel Nehalem processors, the power and heat savings realized by disabling
processor cores allows the remaining cores to run at a higher frequency than their rated speed. In specific application
environments, this may actually increase overall system performance.
Addressing licensing issues. Some software is licensed on a per-core basis. Disabling cores allows an administrator to match
the number of active cores on a server with licensing requirements. However, some software that is licensed on a per-core
basis may not recognize the disabling of cores.
There are no pre-set rules as to when disabling cores may be beneficial. Each server and application environment is unique,
and many factors ultimately influence system performance. An administrator should test each specific application environment to
determine whether disabling processor cores will improve performance and/or lower power consumption.
Additional resources
For additional information on the topics discussed in this article, visit:
HP ROM-Based Setup Utility User Guide
HP Virtual IT Center
Technology and architecture of HP ProLiant
300-series G6 servers
Technology and architecture of HP ProLiant
100-series G6 servers
Understanding and implementing Accelerated iSCSI on HP ProLiant servers
This article focuses on the Internet Small Computer System Interface (iSCSI) protocol, the advantages of HP Accelerated iSCSI,
and the ability to implement Accelerated iSCSI support in the embedded controllers on DL385 G5p, DL385 G6, DL360 G6,
and DL380 G6 servers.
iSCSI protocol
The iSCSI standard implements the SCSI protocol over a TCP/IP network. While iSCSI can be implemented over any TCP/IP
network, the most common implementation is over-1- and 10-Gigabit Ethernet (GbE). The iSCSI protocol transports block-level
storage requests over TCP connections. Using the iSCSI protocol, systems can connect to remote storage and use it as a
physical disk although the remote storage provider or target may actually be providing virtual physical disks.
iSCSI serves the same purpose as Fibre Channel in building SANs, but iSCSI avoids the cost, complexity, and compatibility
issues associated with Fibre Channel SANs. Because iSCSI is a TCP/IP implementation, it is ideal for new field deployments
where no FC SAN infrastructure exists. An iSCSI SAN is typically comprised of software or hardware initiators on the host
connected to an isolated Ethernet network and some number of storage resources (targets). While the target is usually a hard
drive enclosure or another computer, it can also be any other storage device that supports the iSCSI protocol, such as a tape
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c
00191707/c00191707.pdf
www.hp.com/go/g6
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c
00502616/c00502616.pdf
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c
01751718/c01751718.pdf
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