atom feed1 message in org.opensolaris.zfs-discuss[zfs-discuss] zle compression ?
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rolandNov 10, 2009 2:02 pm 
Subject:[zfs-discuss] zle compression ?
From:roland (devz@web.de)
Date:Nov 10, 2009 2:02:53 pm
List:org.opensolaris.zfs-discuss

by some posting on zfs-fuse mailinglist, i came across "zle" compression which
seems to be part of the dedupe-commit some days ago:

http://hg.genunix.org/onnv-gate.hg/diff/e2081f502306/usr/src/uts/common/fs/zfs/zle.c

--snipp 31 + * Zero-length encoding. This is a fast and simple algorithm to eliminate 32 + * runs of zeroes. Each chunk of compressed data begins with a length
byte, b. 33 + * If b < n (where n is the compression parameter) then the next b + 1
bytes 34 + * are literal values. If b >= n then the next (256 - b + 1) bytes
are zero. --snipp

i`m curious - what does that mean?

does zfs have another compression scheme named "zle" now ? if yes, why ?

wasn´t zero-length encoding already there and just a "builtin feature" ?

maybe that builtin has now become an option ?