How WHEA Performs PFA on ECC Memory

Starting with Windows 7, the Windows Hardware Error Architecture (WHEA) supports Predictive Failure Analysis (PFA) for Error Correction Code (ECC) memory.

WHEA performs PFA on ECC memory pages only if the following are true:

• The registry value MemPfaDisable is not set to 1.

• A platform-specific hardware error driver (PSHED) plug-in had not previously set the PlatformPfaControl bit in the WHEA_ERROR_PACKET_FLAGS member of the WHEA_ERROR_PACKET structure to 1. The plug-in sets this bit if it is performing PFA. For more information about how PFA is performed by this plug-in, see PFA Performed by a PSHED Plug-In.

When an ECC memory error occurs on a memory page, WHEA performs PFA on the ECC memory page by following these steps:

1. If WHEA is currently not monitoring the ECC memory page, WHEA adds the page to its monitoring database and clears the error count and tick count for the new entry.

   Note WHEA will stop monitoring an ECC memory page when its tick count exceeds the MemPfaTimeout registry value. When this happens, WHEA removes the entry from its monitoring database.

2. WHEA increments the error count for the ECC memory page.

3. If the error count exceeds the MemPfaThreshold registry value, WHEA first calls the system memory manager to take the ECC memory page offline.

   Note When the system memory manager is called, there is no guarantee that the ECC memory page will actually be taken offline.

WHEA then adds the memory page into the Boot Configuration Data (BCD) in the system store. This prevents the memory page from being used after the next system restart.

Note WHEA will not take a hardware component, such as an ECC memory page, offline if the registry value DisableOffline is set to a nonzero value. Also, WHEA will not add the ECC memory page to the BCD store if the registry value MemPersistOffline is set to 0.

For more information about the PFA registry values for WHEA, see WHEA Policy Settings.

For more information about the system memory manager, see the Memory Management in the Windows SDK documentation.