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Product Features
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
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.
3.7
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 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.
3.10 MicroFemto Slider
These drives incorporate the next generation of femto slider form factor in which the read/write head is
mounted on the small, lightweight microfemto slider that allows the head to move more quickly from
track to track on the disk. WD's microfemto heads enhance tracking and increase shock tolerance,
producing a highly stable high-density drive platform.
20
RELEASED 8/13/13
EX800M
2679-771339-A05
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