A redundant array of independent memory (RAIM) is a design feature found in certain

computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...

s' main

random access memory Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to b ...

. RAIM utilizes additional memory modules and

striping In computer data storage, data striping is the technique of segmenting logically sequential data, such as a file, so that consecutive segments are stored on different physical storage devices. Striping is useful when a processing device request ...

algorithms In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing c ...

to protect against the failure of any particular module and keep the memory system operating continuously. RAIM is similar in concept to a

redundant array of independent disks Raid, RAID or Raids may refer to: Attack * Raid (military), a sudden attack behind the enemy's lines without the intention of holding ground * Corporate raid, a type of hostile takeover in business * Panty raid, a prankish raid by male college ...

(RAID), which protects against the failure of a

disk drive Disk storage (also sometimes called drive storage) is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is ...

, but in the case of memory it supports several DRAM device

chipkill __NOTOC__ Chipkill is IBM's trademark for a form of advanced error checking and correcting (ECC) computer memory technology that protects computer memory systems from any single memory chip failure as well as multi-bit errors from any portion of a ...

s and entire memory channel failures. RAIM is much more robust than

parity checking A parity bit, or check bit, is a bit added to a string of binary code. Parity bits are a simple form of error detecting code. Parity bits are generally applied to the smallest units of a communication protocol, typically 8-bit octets (bytes), ...

and

ECC memory Error correction code memory (ECC memory) is a type of computer data storage that uses an error correction code (ECC) to detect and correct n-bit data corruption which occurs in memory. ECC memory is used in most computers where data corruption c ...

technologies which cannot protect against many varieties of memory failures. On July 22, 2010, IBM introduced the first high end computer server featuring RAIM, the

zEnterprise 196 IBM Z is a family name used by IBM for all of its z/Architecture mainframe computers. In July 2017, with another generation of products, the official family was changed to IBM Z from IBM z Systems; the IBM Z family now includes the newest mo ...

. Each z196 machine contains up to 3 TB (usable) of RAIM-protected main memory. In 2011 the business class model z114 was introduced also supporting RAIM. The formal announcement letter offered some additional information regarding the implementation:

References

{{Reflist, 2 Computer memory Error detection and correction Fault-tolerant computer systems

See also

References