Western Digital WDE2170 - Manual (Page 49)

WD Enterprise WDE2170/WDE4360 Glossary
4079-001045 Rev. B RELEASED 04-08-97 41
Formatted Capacity - 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.
Functional Integrity Testing (FIT) - Suite of tests Western Digital performs on all its drive
products to ensure compatibility with different hosts, operating systems, adapters, application
programs, and peripherals. This testing must be performed before the product can be released to
manufacturing.
Hard Error - Error that cannot be corrected by the error recovery process.
Host Transfer Rate - Speed at which the host computer can transfer data across the SCSI
interface.
Landing Zone - Non-data position on the disk's inner cylinder where the heads land when power
is turned off.
Latency - Average time delay between the head arriving on track and the data rotating to the
head. (Calculated as one-half the revolution period).
Logical Address - Storage location address that may or may not relate directly to a physical
location. The logical address is used when requesting information from a controller. The
controller performs a logical-to-physical address conversion and retrieves the data from a
physical location in the storage device.
MB (Megabyte) - Western Digital defines a megabyte as 1,000,000 bytes.
MTBF (Mean Time Between Failures) - Mean number of life units (in 10 6 hours), during
which all parts of the drive perform within their specified limits, during a particular
measurement interval under stated conditions.
Recoverable Error - Read error, transient or otherwise, that can be corrected by ECC recovery
or by re-reading the data.
RPM (Revolutions per Minute) - Rotational speed of the media (disk), also known as the
spindle speed. Hard drives spin at one constant speed. Disk RPM is a critical component of hard
drive performance because it directly impacts the rotational latency of the disk transfer rate.
SCA-2 - The Single Connector Attach (SCA-2) interface incorporates a grounding contact,
blindmate connector, direct plug misalignment tolerance, ESD protection, hot swap capability,
and backplane connector options. SCA is commonly called the 80-pin connector.
SCSI Configure Automagically (SCAM) - Allows users to attach SCSI devices without
worrying about configuration options.
SCSI-1 - The Small Computer System Interface (ANSI document X3.131-1986).
SCSI-2 - The Small Computer System Interface (ANSI document X3.131-1994).
SCSI-3 - The ANSI X3T10 Working Documents (under development).
SCSI device - Host computer adapter, peripheral controller, or an intelligent peripheral that can
be attached to the SCSI bus.
Sector - A packet of data (usually 512 bytes long).
Seek Time - A measure (in milliseconds) of how fast the hard drive can move its read/write
heads to a desired location.
Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) - Monitors a drive’s
internal status.