X-Received: by 10.180.188.240 with SMTP id gd16mr3815583wic.2.1372112320486; Mon, 24 Jun 2013 15:18:40 -0700 (PDT) Path: csiph.com!usenet.pasdenom.info!news.franciliens.net!news.muarf.org!nntpfeed.proxad.net!proxad.net!feeder1-2.proxad.net!209.85.212.216.MISMATCH!mf3no24918592wib.1!news-out.google.com!md6ni21483wic.0!nntp.google.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Ian Collins Newsgroups: comp.compression Subject: Re: Generating data that can be compressed with a known ratio Date: Tue, 25 Jun 2013 10:18:39 +1200 Lines: 20 Message-ID: References: <8a78d61d-c5aa-4e63-8437-96764a083073@googlegroups.com> <5e3902bf-a25d-4fc8-839a-f1ba129003aa@googlegroups.com> Mime-Version: 1.0 X-Trace: individual.net ND6BhGGNvgkrETaKvd8j9AQTh3Vcjn7nnmOTu2cZs5aNZtriaT Cancel-Lock: sha1:MMF87Ad1lmGFPWOCHRz8nqu4npI= User-Agent: Mozilla/5.0 (X11; SunOS i86pc; rv:17.0) Gecko/17.0 Thunderbird/17.0 In-Reply-To: <5e3902bf-a25d-4fc8-839a-f1ba129003aa@googlegroups.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Xref: csiph.com comp.compression:1986 hitchmanr@gmail.com wrote: > On Monday, June 24, 2013 12:15:13 PM UTC-7, glen herrmannsfeldt > wrote:> >> >> Byte oriented compression algorithms, like LZW, work fine on random >> strings of a subset of the possible bytes. Repeated strings appear >> appropriately more likely as the alphabet size is reduced. > > By "byte oriented", I mean compressors that read and emit series of > bytes (Snappy, LZ4, LZNT1), rather than series of bits, since they > tend to be the only ones fast enough to be used for transparent > compression. The algorithms used by ZFS are LZJB, ZLE, and gzip. Thank's to everyone who has replied, I've probably got enough pointers to start fiddling. -- Ian Collins