Advanced memory protection for HP ProLiant 300 series G4 servers

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Advanced memory protection

for HP ProLiant 300 series G4 servers

Introduction......................................................................................................................................... 2

Protection from memory failures............................................................................................................. 3

Benefits of online spare memory ............................................................................................................ 4

Deployment considerations ................................................................................................................... 4

Implementation differences between ProLiant 300 series G3 and G4 servers .............................................. 4

Dual rank vs. single rank DIMMs ........................................................................................................... 5

Configuration rules for online spare ....................................................................................................... 5

Configuring the AMP mode................................................................................................................... 6

Managing failures in a system with online spare enabled.........................................................................8

Symmetric memory mode.................................................................................................................... 10

Memory Scrubbing ............................................................................................................................ 10

What is memory scrubbing?............................................................................................................ 10

Detailed description of memory scrubbing......................................................................................... 10

Summary of content (12 pages)

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Advanced memory protection for HP ProLiant 300 series G4 servers Introduction......................................................................................................................................... 2 Protection from memory failures............................................................................................................. 3 Benefits of online spare memory ............................................................................................................
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Introduction Advanced Memory Protection (AMP) consists of memory features that provide increased tolerance and protection from memory failures. There are varying levels of AMP that are supported on ProLiant servers, depending on the class of server. Refer to the product QuickSpecs for specific information on the level of features supported on each ProLiant server. AMP features include Advanced ECC, Online Spare Memory, Memory Mirroring and RAID.
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While correctable errors do not affect the normal operation of the system, uncorrectable memory errors will immediately result in a system crash or shutdown of the system when not configured for Mirroring or RAID AMP modes. Uncorrectable errors are detected by ProLiant 300-series servers, but cannot be corrected. ProLiant 500-series and 700-series platforms with Mirroring or RAID AMP support are capable of protecting against uncorrectable memory errors.
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which exceeded the correctable threshold and was deactivated cannot result in an uncorrectable error once the online spare switchover is complete. Benefits of online spare memory With Online Spare Memory, degraded memory is automatically disengaged and a fresh set of memory is used in its place. This brings the reliability of the system to the pre-failure level without any service interruption and without compromising system availability.
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• Memory will automatically be tested in POST whenever the memory configuration has changed (see “Configuring AMP,” below). • RBSU will now allow the system to be configured for Online Spare, even when the DIMM configuration is invalid (see “Configuring AMP,” below). • Correctable threshold errors are still monitored after an Online Spare switchover.
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• On systems that support DDRI DIMMs, dual-rank DIMMs must be populated after single-rank DIMMs. • The last bank populated is the Online Spare bank. • The Online Spare bank must have equal or larger capacity DIMMs to all other DIMMs in the system. See “Note,” below. Note This simple rule is true with HP Memory Option kits. For third party memory, the true requirement is that the Online Spare bank must have greater than or equal to the amount of memory in each rank of the Online Spare bank.
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prevents the user from having to enter RBSU to disable POST speedup, reboot to allow POST to test the memory, and then once again entering RBSU to enable POST speedup. However, just as with the POST memory test, the system must be configured for Advanced ECC to allow the Online Spare bank to be tested. Once the memory has been tested, enable Online Spare: At the prompt at the end of POST, press the F9 key to enter RBSU. From the RBSU main menu, select System Options.
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Online Spare mode does not require operating system support. It can be enabled and function properly with any operating system. In addition, no special software beyond the System BIOS is required for the proper function of Online Spare mode. However, if messaging and logging are desired at the console along with messages in Insight Manager, an operating system must be used that has system management and agent support for AMP.
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As mentioned previously, the ProLiant 300-series G4 servers periodically verify the online spare bank during normal operation. If a potential uncorrectable error in the spare bank is detected, support for switching over to the spare bank will be disabled. The health driver will log a message to the console and to the IML. In addition, the internal health LED will indicate a degraded state, the Online Spare Status LED will illuminate amber, and the DIMM LEDs for the spare DIMMs will illuminate amber.
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Symmetric memory mode Symmetric Memory mode is a performance enhancement supported with certain DIMM configurations on the ProLiant 300-series G4 servers. With either four identical dual-rank DIMMs or eight identical single-rank DIMMs installed in a G4 system configured for Advanced ECC Mode, Symmetric Memory mode will automatically be enabled. When enabled, the system takes advantage of the particular DIMM configuration to improve performance.
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Since the data and ECC bits are written to the DIMM on memory writes, and checked on memory reads. A soft error could result in multiple correctable memory errors occurring if the processor continually read a memory location containing a soft memory error. If a write to that memory location occurred, the error would disappear. However, after the soft error results in the data and ECC bits being out of synch.
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