Hitachi Data Systems
communication is an exactly timed stream of bits when the start of a character is located by using a clocking mechanism such as bipolar encoding. See also Synchronous, Hitachi TrueCopy™.
Availability
In computer science, availability refers to the degree to which a system or resource is capable of performing its normal function. Availability is measured in terms of Mean Time Between Failure (MTBF) divided by MTBF plus the Mean Time to Repair (MTTR). The availability equation is expressed as follows:
AVAILABILITY = MTBF / (MTBF+MTTR).
For example, a server that fails on average once every 5,000 hours and takes an average of two hours to diagnose, replace faulty components and reboot, would have an availability rating of 5,000/(5,000 + 2) = 99.96%. This would correspond to a Level 3 rating using the Scale of 9s.
b
Abbreviation for “bit” where 8 “bits” compose a byte.
B
Abbreviation for byte or the equivalent of one character in text.
Back end
In reference to storage arrays, the back end includes the controllers, disk drives, and paths to the disk drives. On the Lightning 9900™ Series these are the ACP pairs, the Fibre Channel loops, and the Fibre Channel disks.
Business Continuity Planning (BCP)
An “umbrella” term covering both disaster recovery planning and business resumption planning. See also: Disaster Recovery.
Business Impact Analysis (BIA)
The process of analyzing all business functions and the effect that a specific disaster may have upon them.
Business Interruption
Any event, whether anticipated (i.e., public service strike) or unanticipated
(i.e., blackout) that disrupts the normal course of business operations at a corporate location.
CA
Cache Adapter. The CA resides on the cache boards and connects to the Cache Switch (CSW).
52
