Western Digital Purple PR1334M, Техническое справочное руководство

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WD Purple PR1334M Product Features
2679-800084-A04 RELEASED 5/3/17 (WD CONFIDENTIAL) 15
3.5 Perpendicular Magnetic Recording (PMR)
In perpendicular magnetic recording (PMR), the magnetization of each data bit is
aligned vertically to the spinning disk, rather than longitudinally as has been the case
in hard drive technology for decades. In longitudinal recording, as the bits become
smaller and closer together, they experience an increasing demagnetizing field, much
like two bar magnets that are placed end-to-end repel one another. A property of the
media called coercivity must be increased to counteract the demagnetization to keep
the bits stable under thermal fluctuations; otherwise data corruption may occur over
time. Higher media coercivity has pushed the recording head write field to the limit of
known materials.
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.
3.6 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
www.wdc.com/advformat for important
configuration and installation guidelines.