Date: Fri, 23 May 2014 15:10:01 GMT From: Allan Jude <allanjude@freebsd.org> To: freebsd-doc@FreeBSD.org Subject: Re: docs/139336: [request] ZFS documentation suggestion Message-ID: <201405231510.s4NFA1xZ085012@freefall.freebsd.org>
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The following reply was made to PR docs/139336; it has been noted by GNATS. From: Allan Jude <allanjude@freebsd.org> To: bug-followup@FreeBSD.org, zdbs@lif.de Cc: Subject: Re: docs/139336: [request] ZFS documentation suggestion Date: Fri, 23 May 2014 11:05:01 -0400 ZFS compression is completely transparent, so the OS and applications running on top of it are unaware of it. It is safe to compress any files on your system. With the new LZ4 option in ZFS v5000 (FreeBSD 9.2, 8.4 and 10.0 or later), the overhead of the compression is much smaller. In addition to being able to compress at 500mb/s/core and decompress at 1500mb/s/core on a low end i3 laptop processor, LZ4 also has an 'early abort' feature, where if the compression ratio of the block is less than 12.5% after the first ms of attempting to compress it, it aborts and writes the block uncompressed. This means it will not waste a lot of CPU time trying to compress already compressed files like .tar.gz or .mp3 This is documented here: http://www.allanjude.com/zfs_handbook/zfs-term.html#zfs-term-compression And should be committed to the handbook shortly. -- Allan Jude
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