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GLOSSARY
MICROSECOND (µs) – One millionth of a second (.000001 sec.).
MILLISECOND (ms) – One thousandth of a second (.001 sec.).
MTBF – Mean Time Between Failure. Reliability rating indicating the failure rate expected of a product expressed in power on hours (POH). Since manufacturers differ in the ways they determine the MTBF, comparisons of products should always take into account the MTBF calculation method.
MTTR – Mean Time To Repair. The average time it takes to repair a drive that has failed for some reason. This only takes into consideration the changing of the major
N
.NANOSECOND (ns) – One billionth of a second (0.000 000 001 second or
NEXUS – A relationship between two devices that begins with the establishment of an initial connection and ends with the completion of an I/O process. A nexus relationship is further defined by the letters I (initiator), T (target), L (logical unit), R (target routine), x (either L or R), Q (queue tag), and x_y (either an x or a Q)
O
OVERHEAD – Command overhead refers to the processing time required by the controller, host adapter, or drive prior to the execution of a command. Lower command overhead yields higher drive performance. Disk overhead refers to the space required for
OVERWRITE – To write data on top of existing data, erasing it.
OXIDE – A
P
PARITY – An error checking technique wherein the sum of the bits in a data byte is used to set or reset an extra parity bit, depending on whether the sum is an odd or an even number. A second parity check after the data is transferred to a new location checks that the new parity bit matches the transferred bit. Parity checking can only detect an odd number of bit errors (1,3,5, etc.). Parity is defined as odd or even, depending on which condition (odd or even) is used to set the parity bit.
PARKING ZONE – A position in a
PARTITION – A portion of a hard disk dedicated to a particular operating system and application and accessed as a single logical volume.
PERFORMANCE – A measure of the speed of the drive during normal operation. Factors affecting performance are seek times, transfer rate and command overhead.
Maxtor Atlas 10K V