Glossary - Western Digital Purple PR1200M Technical Reference Manual

WD Purple™ PR1200M
8.0 G
LOSSARY
Active LED Status — The WD drive supports external LED requirements. It provides an
activity LED output which is ON during command execution and OFF otherwise.
Annualized Failure Rate (AFR) — A method of measuring failure rates or trends for a group of
units at a site. The rates are based on the monthly total number of returned field failure units
divided by the total cumulative installed base and multiplied by 12 (to annualize the failure
rate).
Advanced Format (AF) — Technology adopted by WD and other drive manufacturers as one
of multiple ways to continue growing hard drive capacities. AF is a more efficient media
format that enables increased areal densities.
AllFrame 4K™ Technology — All WD Purple™ drives are equipped with AllFrame 4K™
technology, which improves ATA streaming to help reduce frame loss, improve overall video
playback, and increase the number of hard drive bays supported within a NVR. Help make
your surveillance solution future-ready knowing that WD Purple™ drives are ready for ultra
high definition cameras.
Automatic Defect Retirement — If defective sectors are found during a read or write, they
are automatically mapped out and relocated.
Block — A group of bytes handled, stored, and accessed as a logical data unit, such as an
individual file record.
Buffer — A temporary data storage area that compensates for a difference in data transfer
rates and/or data processing rates between sender and receiver.
Command Queuing — See Native Command Queuing (NCQ )
Data Lifeguard™ — Representing WD's ongoing commitment to data protection, Data
Lifeguard data protection utilities include thermal management, an environmental protection
system, and embedded error detection and repair features that automatically detect, isolate,
and repair problem areas that may develop over the extended use of the hard drive.
Data Transfer Rate — The rate that digital data is transferred from one point to another,
expressed in bits per second or bytes per second.
Defect Management — A general methodology of eliminating data errors on a recording
surface by mapping out known bad areas of the media.
Dual Stage Actuator Technology — A head positioning system with dual-stage actuators
that improves positioning accuracy over the data track(s). The primary stage provides course
displacement; the secondary stage uses piezoelectric motion to fine tune the head
positioning to a higher degree of precision.
Dynamic Fly Height Control — This feature is designed to compensate for head/media
separation changes due to temperature and altitude. It adds video quality margins across
temperature and altitude changes.
Error Correction Code (ECC) — A mathematical algorithm that can detect and correct errors
in a data field by adding check bits to the original data.
Femto Slider — These drives incorporate the femto slider form factor in which the read/write
head is mounted on the small, lightweight femto slider which allows the head to move more
quickly from track to track on the disk.
F.I.T. (Functional Integrity Testing) — A suite of tests WD performs on all its drive products
to ensure compatibility with different hosts, operating systems, application programs, and
peripherals. This testing must be performed before the product can be released to
manufacturing.
Fluid Dynamic Bearings (FDB) — Bearing design that incorporates a layer of high-viscosity
lubricant instead of ball bearings in the hard drive spindle motor. FDB designs provide
increased non-operational shock resistance, speed control, and improved acoustics.
2679-800065-A03 RELEASED 5/4/17 (WD CONFIDENTIAL)

Glossary

45