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- WHY_ARJ.DOC May 1991
-
-
- This document describes the benefits of ARJ. Pardon the commercial.
- Compression benchmark results are at the end of this document.
-
-
- 1) ARJ provides superior size compression to the other products
- available on the PC. This includes PKZIP 1.10, LHArc 2.12, PAK
- 2.51, ARC 7.00 and HYPER 2.5. In a few particular cases, other
- archivers may produce slightly smaller archives than ARJ. But in
- most cases ARJ provides 1 to 20 percent better compression.
-
- ARJ is particularly strong compressing databases, uncompressed
- graphics files, and large documents. One user reported that in
- compressing a 9.0 megabyte database, PKZIP produced a compressed
- file of size 1.8 megabytes. ARJ produced a compressed file of
- size 1.1 megabytes. Using the maximum compression option, ARJ
- produced a compressed file of size 0.8 megabytes.
-
- 2) Of PKZIP, LHArc, PAK, ARC, ARJ, and HYPER, only ARJ provides the
- capability of archiving files to multiple volume archives. In
- other words, ARJ can archive files directly to diskettes no matter
- how large or how numerous the input files are.
-
- It is possible to archive a 10 megabyte file to several diskettes
- and to recover the file directly from the diskettes. Other
- archivers require that you compress the large file to hard disk
- or large RAM drive and then slice the compressed file to fit on
- diskettes. To recover the original file involves reassembling the
- compressed file on the hard disk from the diskettes and then
- extracting the original file from the reassembled compressed file.
- This option is not even possible if you lack the hard disk space.
-
- This feature makes ARJ especially suitable for distributing large
- software packages without the concerns about fitting entire files
- on one diskette. ARJ will automatically split files when
- necessary and will reassemble them upon extraction.
-
- This multiple volume feature of ARJ makes it suitable as a "poor
- man's" backup utility. ARJ saves pathname information, file
- date-time stamps, and file attributes in the archive volumes. ARJ
- can also create an index file with information about the contents
- of each volume. Files contained entirely within one volume are
- easily extracted using just the one volume.
-
- 3) ARJ provides the facility to store EMPTY directories within its
- archives. This makes it easier to do FULL backups and also to
- distribute software products that come with EMPTY directories.
-
- 4) Both ARJ self-extracting modules provide default pathname support.
- That means that you can build self-extracting archives of software
- directories containing sub-directories. The end user of the
- self-extracting archive does not have to type any command line
- options to restore the full directory structure of the software.
- This greatly simplifies software distribution.
-
- 5) The ARJ archive data structure with its header structure and 32
- bit CRC provide excellent archive stability and recovery
- capabilities.
-
- 6) ARJ provides a security envelope facility to "lock" ARJ archives.
- A "locked" ARJ archive cannot be modified by ARJ. This provides
- some level of assurance to the user receiving a "locked" ARJ
- archive that the contents of the archive have not been tampered
- with. Data integrity checks contribute to the security of the
- ARJ "lock".
-
- 7) The myriad number of ARJ commands and options allow the user
- outstanding flexibility in archiver usage.
-
-
-
- COMPRESSION COMPARISON TEST RESULTS May 26, 1991
-
-
- This benchmark archiver test uses the original PKZIP 1.10 distribution
- archive, PKZ110.EXE, as the base data to compress. The PKZIP 1.10
- distribution archive totals 302196 bytes.
-
-
- ARCHIVER PACKED SIZE COMPRESS TIME EXTRACT TIME
- ---------------- ----------- ------------- ------------
-
- ARJ 2.10 -m4 145374 1:30.9 0:52.0
-
- PAK 2.51 138309 2:26.2 0:53.0
- LHARC 1.13c 137450 4:05.7 1:46.1
- HYPER 2.50 136543 2:30.4 1:54.7
- PKZIP 1.10 136245 2:12.0 0:34.5
- ARJ 2.10 -m3 135185 1:47.2 0:52.1
-
- ARJ 2.10 -m2 130994 1:49.5 0:50.4
- LHA 2.10 130606 2:39.1 0:50.4
-
- ARJ 2.10 (-m1) 129002 2:14.0 0:49.5
- ARJ 2.10 -jm1 128120 2:33.0 0.49.3
- ARJ 2.10 -jm 127992 3:51.8 0.49.3
-
-
- ARJ 2.10 produced the best COMPRESSION SPEED and COMPRESSION SIZE
- results in this test. PKZIP had the fastest EXTRACTION SPEED.
-
- PAK, HYPER, LHARC, and PKZIP compression size results are very
- similar. LHA and ARJ performed significantly better at size
- reduction.
-
- This test was run on a 8 MHz 8088 PC with 20 MB hard drive and 512 K
- ram. The archives were created on and extracted from a ram disk.
-
- end document
-