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EMC Symmetrix DMX-3 Product Guide
Glossary
U
unit address The hexadecimal value that uniquely defines a physical I/O device
on a channel path in an MVS environment. See also device address.
UNIX UNIX is an interactive, multitasking, multiuser operating system.
UNIX is written in “C” language.
There are three types of UNIX files: Directories, data files, and special
files. A directory is a file containing certain information about
another file. A directory contained within another directory is a
subdirectory.
The two most common types of UNIX are BSD (Berkeley Software
Distribution) and System VR4 (developed by AT&T). Most UNIX
systems are a “mix” of both types.
V
vault device A vault device is a volume on a designated physical disk drive for
DMX-3 systems that reserve a dedicated 5 GB space for vaulting data
including metadata.
volume A general term referring to a storage device. In the Symmetrix
subsystem, a volume corresponds to a single disk drive.
W
write hit There is room in global memory for the data presented by the write
operation.
write miss There is no room in global memory for the data presented by the
write operation.
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