Clustering
Disk-to-Disk Backup
Downward
Compatible
FireWire
Hot
Swap Benefit
RAID
Overview
RAID
Comparison
Repeater
Benefits
SAN
Overview
Termination
Basics
Interface
& Connector
Reference
SCSI
Connectors
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Storage Dictionary
- half
duplex
- A data
communications mode which permits transmission in both directions,
but in only one direction at a time.
- half-height
- Refers
to a 1.6" vertical space for a device or device bay,
also approximately half of the vertical space of the full-height
devices. Applies to both 5.25" and 3.5" form factors.
See also full-height or low-profile.
- hard
disk
- A storage
device that uses a magnetic recording material. Generally,
hard disks are fixed inside a PC, but there are removable
cartridge versions too. Hard disks store multiple gigabytes.
- hard
error
- An
error (in data communications or other) that cannot be repaired
by correction schemes.
- hard
wired
- Originally
used to indicate a fixed, permanent hardware connection.
Now expanded to include a selected option, in hardware or
software, which cannot be easily rewired or re-programmed
by the user.
- HD50
- 50-pin
high-density micro-D connector Pin-and-socket connector.
Smaller than the centronics-type. Specified to have spring-latch
fasteners. Male connector used on cables; female on devices.
Often referred to as the "SCSI-2" connector. For more information
Browse to Interface
& Connector Chart or SCSI
Connector Types.
- HD68
- 68-pin
Micro-D high-density - Originally specified in SCSI-3 to
allow the use of one cable for wide (16-bit) applications.
This cable is called a P-cable. 68-pin version of the 50-pin
micro-D high-density connector. Although the 2-56 thumbscrew
fastener is specified in SCSI-3, some manufacturers have
used the spring-latch fastener. Male connector used on cables;
female on devices. Frequently referred to as the "SCSI-3"
connector. For more information Browse to Interface
& Connector Chart
or SCSI
Connector Types.
- head
- The
device which comes in contact with or comes very close to
the magnetic storage device (disk, diskette, drum, tape)
and reads and/or writes to the medium, in computer devices.
Also called the read/write head.
- hex
- Short
for hexadecimal. A number system with a base of 16, designated
by 10 digits and six letters. In hexadecimal notation, the
decimal numbers 0 through 15 are represented by the decimal
digits 0 through 9 and the letters A through F. A=decimal
10, B=decimal 11, and so forth.
- HiPPI
- High
Performance Parallel Interface. An ANSI standard for high-speed
transfer of information in a dual-simplex manner over a
short parallel bus.
- host
- A processor,
usually consisting of a CPU and memory. Typically, a host
communicates with other devices, such as peripherals and
other hosts. On the SCSI bus, a host has a SCSI address
(SCSI ID).
- host
adapter
- Circuitry
that translates between a processor's internal bus and a
different bus, such as SCSI. On the SCSI bus, a host acts
as an Initiator and a peripheral acts as a Target.
- hot
swap
- Physical
hardware replacement without powering off the system. Browse
to Hot Swap for
more information.
- HTTP
- Hyper Text Transport Protocol
- The
method of accessing data over the web typically for display
of information in web pages.
- Hz
- Abbreviation
for Hertz; cycles per second.
- HVD
- High
Voltage Differential interface, in the past referred to
simply as Differential.
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