HP ML100 - Manual (Page 26)

• Lockstep—provides enhanced protection while making all installed memory available to the
operating system. The server can continue to function if a single- or mulit-bit memory failure within a
single DRAM device occurs.
Advanced Memory Protection options are configured in RBSU. If the requested AMP mode is not
supported by the installed DIMM configuration, the server boots in Advanced ECC mode. For more
information, see "HP ROM-Based Setup Utility ("ROM-Based Setup Utility" on page 38)."
For the latest memory configuration information, see the QuickSpecs on the HP website
(http://www.hp.com).
RDIMM maximum memory configurations
The following table lists the maximum memory configuration possible with 4-GB RDIMMs.
Rank Single-processor Dual-processor
Single-rank 24 GB 48 GB
Dual-rank 24 GB 48 GB
Quad-rank 24 GB 48 GB
UDIMM maximum memory configurations
The server supports a maximum of 12 GB with one processor and 24 GB with two processors using 2-GB
single- or dual-rank UDIMMs.
Advanced ECC memory configuration
Advanced ECC memory is the default memory protection mode for this server. Standard ECC can correct
single-bit memory errors and detect multi-bit memory errors. When multi-bit errors are detected using
Standard ECC, the error is signaled to the server and causes the server to halt.
Advanced ECC protects the server against some multi-bit memory errors. Advanced ECC can correct both
single-bit memory errors and 4-bit memory errors if all failed bits are on the same DRAM device on the
DIMM.
Advanced ECC provides additional protection over Standard ECC because it is possible to correct certain
memory errors that would otherwise be uncorrected and result in a server failure. The server provides
notification that correctable error events have exceeded a pre-defined threshold rate.
Lockstep memory configuration
Lockstep mode provides protection against multi-bit memory errors that occur on the same DRAM device.
Lockstep mode can correct any single DRAM device failure on x4 and x8 DIMM types. The DIMMs in
each channel must have identical HP part numbers.
Lockstep mode uses channel 1 and channel 2. Channel 3 is not populated. Because channel 3 cannot be
populated when using Lockstep mode, the maximum memory capacity is lower than Advanced ECC
mode. Memory performance with Advanced ECC is also slightly higher.
General DIMM slot population guidelines
Observe the following guidelines for all AMP modes:
Hardware options installation 26