I am sponsoring the following case for Alok Aggarwal. Requested
binding is minor, matching the binding for the original lofiadm
compression case (PSARC/2007/569).
This is a straight-forward addition allowing a new compression
algorithm to be used with lofiadm. I believe this case qualifies as
self-review, and have submitted it as such. If there is disagreement,
please let me know and I will change it to a regular fast-track.
Template Version: @(#)sac_nextcase %I% %G% SMI
This information is Copyright 2008 Sun Microsystems
1. Introduction
1.1. Project/Component Working Name:
LZMA compression for lofi
1.2. Name of Document Author/Supplier:
Author: Alok Aggarwal
1.3 Date of This Document:
19 December, 2008
4. Technical Description
This case proposes to add another compression algorithm to the
list of supported algorithms for lofiadm(1M).
Currently, lofiadm(1M) allows compression algorithms to be specified
via the '-C' command line option. gzip-6 and gzip-9 are the two
supported algorithms. This case intends to add support for LZMA
(Lempel-Ziv Markov chain algorithm) as well.
Rationale for adding LZMA as a supported algorithm:
The LZMA algorithm offers distinct advantages in compressing binary
data, it provides a much higher compression ratio than, say, gzip or bzip2.
Our testing shows that it compresses between 30-40% better than gzip-9.
Related CR:
The work described as part of this case will be delivered with the
following CR:
6785864 lzma compression support for lofi
6785871 lofiadm(1M) should mention lzma as a supported compression algorithm
Command Changes
The '-C' option to lofiadm(1M) will take an additional optional parameter.
The changes are as follows -
SYNOPSIS
[...]
/usr/sbin/lofiadm -C algorithm [-s segment_size] file <----
[...]
OPTIONS
[...]
-C {gzip | gzip-N | lzma} |
Compress the file with the specified compression algo- |
rithm. |
The gzip compression algorithm uses the same compression
as the open-source gzip command. You can specify the
gzip level by using the value gzip-N where N is 6 (fast)
or 9 (best compression ratio). Currently, gzip, without |
a number, is equivalent to gzip-6 (which is also the |
default for the gzip command).
lzma stands for the LZMA (Lempel-Ziv-Markov) compression |
algorithm.
References
PSARC/2007/569 - lofi(7D) compression support
http://sac.sfbay/Archives/CaseLog/arc/PSARC/2007/569
PSARC/1999/463 - lofi
http://sac.sfbay/Archives/CaseLog/arc/PSARC/1999/463
LZMA numbers
http://blogs.sun.com/aalok/entry/lzma_compression
6. Resources and Schedule
6.4. Steering Committee requested information
6.4.1. Consolidation C-team Name:
ON
6.5. ARC review type: Automatic
6.6. ARC Exposure: open
