Notouch Ramp Load Technology; Dual Stage Actuator Technology; Advanced Format (Af); Native Command Queuing (Ncq) - Western Digital Purple PR1200M Technical Reference Manual

WD Purple™ PR1200M
3.6

NoTouch Ramp Load Technology

Parks the recording heads 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

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 piezo electric motion to fine tune the head positioning to a
higher degree of precision.
3.8

Advanced Format (AF)

Advanced Format (AF) technology is 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.
In AF, each physical sector is composed of eight 512 byte logical sectors, totaling
4096 bytes. WD is shipping AF drives as 512 Byte Emulated Devices until full
operating system support for the AF host interface is available. 512 Byte Emulated
Device drives are backward compatible with 512 byte sector accesses.
WD AF hard drives may require you to run the WD Align software utility after you
install your operating system or partition and format the drive as a secondary drive.
WD Align software aligns partitions on the AF drive to ensure it provides full
performance for certain configurations. Go to
configuration and installation guidelines.
3.9 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.

3.10 Preemptive 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 disk lubricant maintains an even distribution and does
not become depleted. This feature ensures reliability for applications that perform a
high incidence of read/write operations at the same physical location on the disk.
2679-800065-A03 RELEASED 5/4/17 (WD CONFIDENTIAL)
for important
www.wdc.com/advformat
Product Features
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