From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263478AbTJQOxY (ORCPT ); Fri, 17 Oct 2003 10:53:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263487AbTJQOxY (ORCPT ); Fri, 17 Oct 2003 10:53:24 -0400 Received: from zeke.inet.com ([199.171.211.198]:2996 "EHLO zeke.inet.com") by vger.kernel.org with ESMTP id S263478AbTJQOxW (ORCPT ); Fri, 17 Oct 2003 10:53:22 -0400 Message-ID: <3F90025A.7070504@inet.com> Date: Fri, 17 Oct 2003 09:53:14 -0500 From: Eli Carter User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.2) Gecko/20030708 X-Accept-Language: en-us, en MIME-Version: 1.0 To: John Bradford CC: jw schultz , linux-kernel@vger.kernel.org Subject: Re: Transparent compression in the FS References: <1066163449.4286.4.camel@Borogove> <20031015133305.GF24799@bitwizard.nl> <3F8D6417.8050409@pobox.com> <20031016162926.GF1663@velociraptor.random> <3F8ECA3E.4030208@draigBrady.com> <20031016231235.GB29279@pegasys.ws> <200310170803.h9H83ahx000164@81-2-122-30.bradfords.org.uk> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org John Bradford wrote: >>What might be worth considering is internal NUL detection. >>Build the block-of-zeros detection into the filesystem >>write resulting in automatic creation of sparse files. >>This could even work with extent based filesystems where >>using hashes to identify shared blocks would not. > > > Another idea could be writing uncompressed data to the disk, and > background-compressing it with something like bzip2, but keeping the > uncompressed data on disk as well, only over-writing it when disk > space is low, and then overwriting the least recently used files > first. > > The upshot of all that would be that if you needed space, it would be > there, (just overwrite the uncompressed versions of files), but until > you do, you can access the uncompressed data quickly. > > You could even take it one step further, and compress files with gzip > by default, and re-compress them with bzip2 after long periods of > inactivity. Note that a file compressed with bzip2 is not necessarily smaller than the same file compressed with gzip. (It can be quite a bit larger in fact.) Eli --------------------. "If it ain't broke now, Eli Carter \ it will be soon." -- crypto-gram eli.carter(a)inet.com `-------------------------------------------------