HP ProLiant Intel-based 100-series G6 servers

If an uncorrectable error occurs, the system automatically directs the read to the mirrored location to

obtain the correct data. Since each mirrored DIMM is one of a pair, one DIMM can be protected by

mirroring while another is degraded. As a result, even after mirroring is degraded by a DIMM failure,

the other DIMM in the mirrored pair is still protected by Advanced ECC. The OS does not revert to

Advanced ECC Mode until the failed DIMM is replaced and the server rebooted.

Memory channel interleaving

Xeon 340

0, 5500, and 5600 Series processors retrieve data from the memory DIMMs in 64-byte

chunks. With channel interleaving, the system is set up so that each consecutive 64-byte chunk in the

memory map is physically transferred by means of alternate routing through the three available data

channels.

The result is that when the memory controller needs to access a block of logically contiguous memory,

the requests are distributed more evenly across the three channels rather than potentially stacking up

in the request queue of a single channel. This alternate routing decreases memory access latency and

increases performance. However, interleaving memory channels increases the probability that more

DIMMs need to be kept in an active state (requiring more power) since the memory controller

alternates between channels and between DIMMs. This is discussed further in the “Power and thermal

technologies” section.

Lockstep memory mode

Lockstep mod

e is an advanced memory protection feature supported in ProLiant Intel 100-series G6

servers using the Xeon 5500 and 5600 Series processors. It uses two of the processor's three memory

channels to provide an even higher level of protection than Advanced ECC. In lockstep mode, two

channels operate as a single channel—each write and read operation moves a data word two

channels wide. The cache line is split across both channels to provide 2x 8-bit error detection and 8-

bit error correction within a single DRAM. In three-channel memory systems, the third channel is

unused and left unpopulated. The Lockstep Memory mode is the most reliable memory protection

method, but it reduces the total system memory capacity by a third in most systems. Performance is

measurably slower than normal Advanced ECC mode, and uncorrectable memory errors can only be

isolated to a pair of DIMMs instead of a single DIMM. Lockstep mode is not the default operation;

administrators must enable it in BSU.

For additional information about DDR3 memory, see the technology brief titled “Memory technology

evolution: an overview of system memory technologies” at

http://

h20000.www2.hp.com/bc/docs/support/SupportManual/c00256987/c00256987.pdf.

NOTE:

Memory mirroring with DDR3 and Lockstep memory mode are not supported on the

DL1000 Multi Node server

I/O technologies

ProLiant 100-series G6 servers incorporate PCI Express, Serial-Attached SCSI (SAS), and Serial ATA

(SATA) I/O technologies. PCI Express lets administrators add expansion cards with various

capabilities to the system. SAS is a serial communication protocol for direct-attached storage devices

such as SAS and SATA hard drives.