C-Glossary
Read Ahead Cache Motivated by the principle of “spatial locality”, many RAID controllers read blocks of data from secondary storage ahead of time, i.e., before an application actually requests those blocks. The number of data blocks that are read ahead of time is typically governed by some heuristic that observes the pattern of requests. The
Read Through Cache Using this methodology, a read operation not only reads data from secondary storage into system memory but also places the data into the cache such that future need for the same data can be addressed expeditiously by directing a read operation for that data into the cache only.
RAID Rebuild When a RAID array enters into a degraded mode, it is advisable to rebuild the array and return it to its original configuration (in terms of the number and state of working disks) to ensure against operation in degraded mode
SATA Acronym for “Serial ATA”. A hard disk drive interface standard developed to enhance connectivity and speed over the IDE, or Parallel ATA disk interface. Current generation SATAII supports speeds up to 300MB/S.
Stripe A stripe is a logical space that spans across multiple hard disks with each constituent hard disk contributing equal strips (or chunks) of space to the stripe. In the figure below, strips 1, 2, and 3 from hard disk 1, 2, and 3 respectively comprise a (purple colored) stripe. Synonym: major stripe
Stripe Set A stripe set is a set of stripes that spans across multiple hard disks. In the figure below, the displayed stripe set has 4 stripes, with strip number 1 comprised of the purple strips 1A, 1B and 1C. Stripe number 2 is comprised of the green strips 2A, 2B and 2C etc.
Stripe Size This is the size of the strips that constitute each stripe. This term is a misnomer – though prevalent – since it should appropriately be called strip size or chunk size.
TCP/IP This is an acronym for “Transmission Control Protocol/Internet Protocol”. It is comprised of two parts TCP and IP. The former, i.e., TCP is a
Universal Serial Bus (USB) is a specification created in 1996 by a consortium of companies led by Intel to simplify the connection between host computer and peripheral devices. The original USB 1.x specification was capable of 12 Mbit/sec. USB 2.0 is the most common port at time of publication, and is capable of 480Mbit/sec gross bandwidth. USB 3.0 was ratified in November of 2008, and is capable of 5Gbit/sec gross bandwidth.
Volume Set A volume set is a concatenation of storage elements that may be RAID arrays, JBODs, or simply areas of disks that are not part of RAID arrays.
RAIDBank5 Owner’s Manual | 44 |