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Memory Mirror and Memory Patrol

Related Products : SPARC M10-1, M10-4, M10-4S

Memory data protection by ECC and Extended ECC

Memory data is protected by ECC and Extended ECC.

ECC (Error Checking and Correction)

ECC is a data protection mechanism which recovers single bit errors by accurate detection and correction of corrupted data. It works by adding an ECC code to each data block.

Extended ECC (*1)

Extended ECC uses an ECC-like mechanism to rescue data left on faulty memory chips (DRAM).

*1: This corresponds to IBM's Chipkill function.

Memory Mirror provides memory redundancy

SPARC M10 incorporates a memory redundancy mechanism. Referred to as "Memory Mirror", it improves single system reliability using ECC to protect all data in memory, even from uncorrectable multi-bit errors. Memory Access Controllers equipped in processors help mirror memory chips.

SPARC64 X Memory Mirror

Memory Mirroring Actions

Data is written to both sides of the memory mirror at the same time (Memory A and Memory B).

As data is read its validity is checked using ECC. If no error is found the Memory Access Controller reconfirms data validity by comparing data in memory A and B. If an uncorrectable error is detected in memory A, data in memory B is used for the read operation, and vice versa.

SPARC64 X Memory Mirror Action

Memory Patrol fast and early error detection

A memory check function in hardware detects and corrects memory errors, downgrades memory and avoids OS or application failure caused by faulty memory chips (*2). This hardware function in the Memory Access Controller enables fast memory checking without consuming OS or CPU resources.

SPARC64 X Memory Mirror Patrol

*2: Also referred to as “memory scrubber”