ECC scrubbing
A background process in ECC memory systems that periodically reads through all RAM, detects and corrects single-bit errors before they have time to accumulate into uncorrectable double-bit errors. Preventive maintenance against silent data corruption in servers.
Problem: ECC memory can correct single-bit errors (a flipped bit, often caused by cosmic radiation or electrical noise) but only detect — not correct — double-bit errors. The risk: if a bit flips in rarely-read memory and sits uncorrected, and later a SECOND bit in the same word flips, it becomes an uncorrectable double error → a crash or corruption. ECC scrubbing ("patrol scrub") counters this: the memory controller systematically reads through all memory in the background, and every single-bit error it finds is corrected and written back correctly → errors never get to sit and accumulate. It runs at low priority so it doesn't disturb performance. Crucial in servers and systems with large amounts of memory (more bits = more radiation hits) and long uptime. A complement to the actual ECC correction on read. Related to ECC memory and memory controller.