WD Scorpio ML160M
Product Features
2679-701205-A00
RELEASED 1/16/09 (WD CONFIDENTIAL)
13
3.0
P
RODUCT
F
EATURES
Perpendicular Magnetic Recording (PMR)
Reduced Power Spinup (RPS)
Ramp Load/Unload (LUL)
System-on-Chip (SOC)
S.M.A.R.T. Command Transport (SCT)
Reliability Features Set—Data Lifeguard™
Fluid Dynamic Bearings (FDB)
CacheFlow™
Dual Drive Option
Power Management
High-Speed Data Transfer Support
Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.)
Security Mode
Automatic Acoustic Management (AAM)
3.1
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.
3.2
Reduced Power Spinup (RPS)
Applications for 2.5-inch hard drives like the WD Scorpio include USB external hard drives,
notebook systems, and Consumer Electronics (CE). Due to the fact that many of these
applications are portable in nature, an option for limiting startup current levels and increasing
spinup speed is necessary.
