[KLUG Members] Re: drive ghosting -- Recommend LZO compression

[Bryan J. Smith]

Bruce Smith wrote:
> I don't [compress].  (except for files on disk)
> I believe find|cpio & tar both are limited by the speed
> of my disks.

BTW, I recommend you download and compile LZO/Lzop regardless.

Gzip (LZ77) and Bzip2 (BWT) which still take 2-4x and 5-10x longer,
respectively, to tarball/afio stuff on my dual-Athlon 1.4GHz than
just plain Tar (on compression).  So the reduction in size and
reduced disk writes times is not enough to overcome the increased
CPU load (for the compression algorithm) to even benefit me on my
dual-Athlon.

But Lzop (LZO) uses a "real-time" compression algorithm.  What this
means is that the reduction in size and reduced disk write times
_does_ make a difference, at least on my dual-Athlon.  The
"trade-off" is a slight compression ratio loss, but still better
than none.  So LZO ends up being both _smaller_ *AND* _faster_ than
no compression.  And the LZO algorithm is great at detecting
pre-compressed file formats (especially graphics) which is either
skips or uses a "alternate/quick" algorithm on (instead of using the
same algorithm to net you only 3-5% smaller like GZip).

For a comparison of Gzip (LZ77), Bzip2 (BWT) and Lzop (LZO), see
this post:
http://www.matrixlist.com/pipermail/leaplist/2001-December/016244.html

-- Bryan

-- 
Bryan J. Smith, Engineer        mailto:b.j.smith@ieee.org   
AbsoluteValue Systems, Inc.     http://www.linux-wlan.org
SmithConcepts, Inc.          http://www.SmithConcepts.com
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