HP ProLiant BL420c HP ProLiant BL420c Gen8 Server Blade User Guide - Page 32

is degrading. This allows DIMMs that have a higher probability of receiving an uncorrectable memory error (which would result in system downtime) to be removed from operation. Advanced Memory Protection options are configured in RBSU. If the requested AMP mode is not supported by the installed DIMM configuration, the server blade boots in Advanced ECC mode. For more information, see "HP ROM-Based Setup Utility (on page 56)." The server blade also can operate in independent channel mode or combined channel mode (lockstep). When running in lockstep mode, you gain reliability in one of two ways: • If running with UDIMMs (built with x8 DRAM devices), the system can survive a complete DRAM failure (SDDC). In independent channel mode, this failure would be an uncorrectable error. • If running with RDIMM (built with x4 DRAM devices), the system can survive the complete failure of two DRAM devices (DDDC). Running in independent mode, the server can only survive the complete failure of a single DRAM device (SDDC). Maximum capacity DIMM type RDIMM RDIMM LRDIMM UDIMM UDIMM DIMM rank Single-rank Dual-rank Quad-rank Single-rank Dual-rank One processor 48 GB 96 GB 192 GB 12 GB 48 GB Two processors 96 GB 192 GB 384 GB 24 GB 96 GB For the latest memory configuration information, see the QuickSpecs on the HP website (http://www.hp.com). Advanced ECC memory configuration Advanced ECC memory is the default memory protection mode for this server blade. 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 blade and causes the server blade to halt. Advanced ECC protects the server blade 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 blade failure. Using HP Advanced Memory Error Detection technology, the server blade provides notification when a DIMM is degrading and has a higher probability of uncorrectable memory error. Online Spare memory configuration Online spare memory provides protection against degraded DIMMs by reducing the likelihood of uncorrected memory errors. This protection is available without any operating system support. Online spare memory protection dedicates one rank of each memory channel for use as spare memory. The remaining ranks are available for OS and application use. If correctable memory errors occur at a rate higher than a specific threshold on any of the non-spare ranks, the server blade automatically copies the memory contents of the degraded rank to the online spare rank. The server blade then deactivates the failing rank and automatically switches over to the online spare rank. Hardware options installation 32