Ultrastar 7K2
HGST Hard Disk Drive Technical Reference Manual
49
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LOSSARY
Active LED Status
— The HGST drive supports external LED requirements. It provides an activity LED output
which is ON during command execution and OFF otherwise.
Annualized Failure Rate (AFR)
— A method of measuring failure rates or trends for a group of units at a site. The
rates are based on the monthly total number of returned field failure units divided by the total cumulative installed
base and multiplied by 12 (to annualize the failure rate).
Automatic Defect Retirement
— If defective sectors are found during a read or write, they are automatically
mapped out and relocated.
Block
— A group of bytes handled, stored, and accessed as a logical data unit, such as an individual file record.
Buffer
— A temporary data storage area that compensates for a difference in data transfer rates and/or data
processing rates between sender and receiver.
Data Lifeguard™
— Representing the ongoing commitment to data protection, Data Lifeguard data protection
utilities include thermal management, an environmental protection system, and embedded error detection and
repair features that automatically detect, isolate, and repair problem areas that may develop over the extended use
of the hard drive.
Data Transfer Rate
— The rate that digital data is transferred from one point to another, expressed in bits per second
or bytes per second. Data Transfer Rate to Disk: The internal disk transfer rate in Mbits per second. Data Transfer Rate
from the Buffer to the Host: Based on the transfer of buffered data in MB per second.
Defect Management
— A general methodology of eliminating data errors on a recording surface by mapping out
known bad areas of the media.
Data Path Protection (DPP)
— A feature that prevents possible electronic failures by preventing corruption of data
on the hard drive.
Dual Stage Actuator (DSA)
— DSA is an improvement to the overall capability of the Servo system and
provides a mechanical benefit to improve the response time (higher Bandwidth capability) of moving and
maintaining the head position over the data tracks.
ECC On-the-Fly
— HGST utilizes an LDPC hardware correction technique that corrects errors prior to host transfer
without any performance penalties. These error corrections are invisible to the host system because they do not
require assistance from the drive’s firmware.
Error Correction Code (ECC)
— A mathematical algorithm utilizing LDPC technology that can detect and correct
errors in a data field by adding check bits to the original data.
F.I.T. (Functional Integrity Testing)
— A suite of tests HGST performs on all its drive products to ensure
compatibility with different hosts, operating systems, application programs, and peripherals. This testing must be
performed before the product can be released to manufacturing.
Fluid Dynamic Bearings (FDB)
— Bearing design that incorporates a layer of high-viscosity lubricant instead of
ball bearings in the hard drive spindle motor. FDB designs provide increased non-operational shock resistance,
speed control, and improved acoustics.
Formatted Capacity
— The actual capacity available to store data in a mass storage device. The formatted
capacity is the gross capacity minus the capacity taken up by the overhead data required for formatting the
media.
Hot Plugging
— The ability to swap out a failed hard drive without having to power down the system or reboot.
IntelliSeek
—The technology that proactively calculates an optimum seek speed to eliminate hasty movement of
the actuator that produces noise and requires power.
Latency
— The period of time that the read/write heads wait for the disk to rotate the data to an accessible position.
For a disk rotating at 10,000 RPM, the average latency is 3 milliseconds.
Logical Block Address
— An alternative addressing methodology of identifying a given location on a SATA
drive that permits disk sizes greater than 528 MB.
