COMPRESSASM(8) Legato NetWorker 3.0 COMPRESSASM(8)
NAME
compressasm - NetWorker module for compressing and decompressing
files
SYNOPSIS
compressasm [standard-asm-arguments]
DESCRIPTION
The compressasm is a standard, external ASM (Application Specific
Module) used to compress files when they are saved and decompress
files when they are recovered. See uasm(8) for a general description
of ASM's and the [standard-asm-arguments].
It is intended that compressasm be invoked by uasm during save(8) or
recover(8) operations.
The compressasm uses a Legato implementation of Lempel-Ziv compres
sion coding to compress file pages (one page is always 8 Kbytes)
while saving them. This can result in less data being transmitted
over the network and less data being stored. Since the network and
media subsystems are normally important performance bottlenecks, this
can provide significant performance improvement, especially if the
client processor is relatively fast. Compressions of 50-60% are typ
ical, but results vary with the content of the file.
The per page compression technique will never cause data expansion.
Since compression occurs on a per page basis, the efficiency of com
pressasm may be less than that of compress(1).
Upon recovery, files are decompressed into their original form.
SEE ALSO
compress(1), save(8), recover(8), uasm(8)
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