Intelliseek; Notouch Ramp Load Technology; Stabletrac (Double-Tied Shaft Motor); Native Command Queuing (Ncq) - Western Digital WD1002FBYS Technical Reference Manual

Product Features
In perpendicular recording, the adjacent bits attract instead of repel (as with bar magnets
placed side by side,) creating more thermally stable bits. In addition, the media contains a
magnetically soft underlayer (SUL) beneath the recording layer. This SUL allows a larger
effective write field, thus higher coercivity media, enabling further increases in density. Lastly,
because of the vertical orientation of the bits, the PMR recording layer tends to be thicker than
that used for longitudinal recording, providing increased signal for the read heads. All of these
benefits enable WD engineers to reliably pack more data on a given disk than is possible with
conventional longitudinal recording.
3.5

IntelliSeek

WD's unique IntelliSeek technology proactively calculates an optimum seek speed to
eliminate hasty movement of the actuator that produces noise and requires power, which is
common in other drives. With IntelliSeek, the actuator's movement is controlled so the head
reaches the next target sector just in time to read the next piece of information, rather than
rapidly accelerating and waiting for the drive rotation to catch up. This smooth motion reduces
power usage by more than 60 percent compared with standard drives, as well as quiets seek
operation and lowers vibration.
3.6

NoTouch Ramp Load Technology

This feature delivers lower power consumption by automatically unloading the heads during
idle to reduce aerodynamic drag. The recording heads are parked off the disk surface during
spin up, spin down and when the drive is off. This ensures the recording head never touches
the disk surface resulting in improved long term reliability due to less head wear, and improved
non-operational shock tolerance.
3.7

StableTrac (Double-tied Shaft Motor)

Used exclusively on WD high-capacity hard drives, StableTrac motors feature both top and
bottom attachment points, which lowers susceptibility to mistracking or misreading data by
system-induced vibration. Most current hard drive designs feature motors that are only
attached on the bottom of the hard drive. StableTrac allows user data to be found fast without
encountering issues of missed revolutions, which is inherent in some designs.
3.8

Native Command Queuing (NCQ)

These drives support Native Command Queuing. NCQ is a true Enterprise feature for
environments such as database, Web servers, and e-mail servers.
Performance of a random I/O workload can be improved through intelligent re-ordering of the
I/O requests so they read/write to and from the nearest available sectors and minimize the
need for additional disk revolutions or head actuator movement. This improvement is achieved
though Native Command Queuing (NCQ).
NCQ allows the drive to re-order read commands, thereby increasing random read IOPs.
Additional NCQ features that can prove beneficial include a Write Cache disabled IOP
increase and a queuing implementation built upon an existing, highly automated cache
architecture. Queued reads in NCQ leverage the same re-ordering schemes used for write
caching. The firmware design maintains the "order" of overlapping/colliding queued
commands. NCQ is designed to excel in multi-threaded environments with high random I/O
loads.
3.9

Pre-emptive Wear Leveling (PWL)

This WD feature provides a solution for protecting the recording media against mechanical
wear. In cases where the drive is so busy with incoming commands that it is forced to stay in
a same cylinder position for a long time, the PWL control engine initiates forced seeks so that
18 RELEASED 11/13/08 (WD CONFIDENTIAL)
WD RE3 XL333M
2679-701179-A01