Product Features
WD Scorpio MX375M
14
RELEASED 11/17/10 (WD CONFIDENTIAL)
2679-771293-A01
3.1
SATA 3 Gb/s
SATA 3 Gb/s is the next generation interface for SATA hard drives. It adds to the functionality of the
SATA I interface with the following features:
Improved Power Management
— provides improved power management features including
Host Initiated SATA Power Management (HIPM) and Device Initiated SATA Power
Management (DIPM).
Staggered Spin-up
— allows the system to control whether the drive will spin up immediately
or wait until the interface is fully ready before spinning up.
Asynchronous Signal Recovery (ASR)
— robustness feature that improves signal
recovery.
Enclosure Services
— defines external enclosure management and support features.
Backplane Interconnect
— defines how to lay out signal line traces in a backplane.
Auto-activate DMA
— provides increased command efficiency through automated activation
of the DMA controller.
Device Configuration Overlay (DCO)
— allows hiding of supported features via a SATA
feature mask.
3.2
Perpendicular Magnetic Recording (PMR-Writer)
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.
