From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: Re: Inefficient storing of ISO images with compress=lzo Date: Mon, 19 Sep 2011 11:13:19 +0800 Message-ID: <4E76B34F.9030206@cn.fujitsu.com> References: <1316388769.2499.4.camel@picard> <4E76AEB9.4080109@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: linux-btrfs@vger.kernel.org To: uzytkownik2@gmail.com Return-path: In-Reply-To: <4E76AEB9.4080109@cn.fujitsu.com> List-ID: Li Zefan wrote: > Maciej Marcin Piechotka wrote: >> I've noticed that: >> >> - with x86-64 Fedora 15 DVD install images: >> - du -sh was 36 GB >> - btrfs df | grep -i data have shown over 40 GB used >> - without >> - du -sh is 34 GB >> - btrfs df | grep -i data have shown less then 34 GB used >> >> It seems that iso files are considered compressable while they may not be (and penalty is severe - 3x). >> > > With compress option specified, btrfs will try to compress the file, at most > 128K at one time, and if the compressed result is not smaller, the file will > be marked as uncompressable. > > I just tried with Fedora-14-i386-DVD.iso, and the first 896K is compressed, > with a compress ratio about 71.7%, and the remaining data is not compressed. > correct: the compression ratio is 38.3%, pretty good :)