Editing Memory scrubbing (section)

{{More citations needed|date=February 2015}}

'''Memory scrubbing''' consists of reading from each [[computer memory]] location, correcting [[bit error]]s (if any) with an error-correcting code ([[Error detection and correction#Error-correcting code|ECC]]), and writing the corrected data back to the same location.<ref>
Ronald K. Burek.
[http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.132.2475&rep=rep1&type=pdf "The NEAR Solid-State Data Recorders"].
Johns Hopkins APL Technical Digest.
1998.
</ref>

Due to the high integration density of modern computer memory [[Integrated circuit|chips]], the individual memory cell structures became small enough to be vulnerable to [[cosmic ray]]s and/or [[alpha particle]] emission.  The errors caused by these phenomena are called [[soft error]]s. Over 8% of DIMM modules experience at least one correctable error per year.<ref>[https://www.cs.toronto.edu/~bianca/papers/sigmetrics09.pdf DRAM Errors in the Wild: A Large-Scale Field Study]</ref> This can be a problem for [[Dynamic random-access memory|DRAM]] and [[Static random-access memory|SRAM]] based memories.  The probability of a soft error at any individual memory bit is very small.  However, together with the large amount of memory modern computers{{mdashb}}especially [[Server (computing)|servers]]{{mdashb}}are equipped with, and together with extended periods of [[uptime]], the probability of soft errors in the total memory installed is significant.{{citation needed|date=July 2017}}

The information in an [[ECC memory]] is stored [[Redundancy (information theory)|redundantly]] enough to correct single bit error per memory word.  Hence, an ECC memory can support the scrubbing of the memory content. Namely, if the [[memory controller]] scans systematically through the memory, the single bit errors can be detected, the erroneous bit can be determined using the ECC [[error detection and correction|checksum]], and the corrected data can be written back to the memory.