main memory (DRAM-based) is capable of scrubbing but also the CPU caches (SRAM-based). On most systems the scrubbing rates for both can be set independently. Because cache is much smaller than the main memory, the scrubbing for caches does not need to happen as frequently. Memory scrubbing increases reliability, therefore it can be classified as a RAS feature. Variants There are usually two variants, known as patrol scrubbing and demand scrubbing. While they both essentially perform memory scrubbing and associated error correction (if it is doable), the main difference is how these two variants are initiated and executed. Patrol scrubbing runs in an automated manner when the system is idle, while demand scrubbing performs the error correction when the data is actually requested from main memory. See also Data scrubbing, a general category containing memory scrubbing Soft error, an important reason for doing memory scrubbing Error detection and correction, a general theory used for memory scrubbing Memory refresh, which preserves information stored in memory References Computer memory