From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55817) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VN0gb-0005QY-IO for qemu-devel@nongnu.org; Fri, 20 Sep 2013 09:23:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VN0gV-0000n7-JN for qemu-devel@nongnu.org; Fri, 20 Sep 2013 09:23:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24861) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VN0gV-0000mz-A8 for qemu-devel@nongnu.org; Fri, 20 Sep 2013 09:23:47 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r8KDNksC014079 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 20 Sep 2013 09:23:46 -0400 Date: Fri, 20 Sep 2013 09:23:44 -0400 From: Jeff Cody Message-ID: <20130920132344.GM15106@localhost.localdomain> References: <072dca92f6fa9125b3e8e34e07141cef06d4ff56.1379648036.git.jcody@redhat.com> <523C43C0.8030907@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <523C43C0.8030907@redhat.com> Subject: Re: [Qemu-devel] [PATCH 1/2] block: qemu-iotests - add basic ability to use binary sample images List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: kwolf@redhat.com, famz@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com On Fri, Sep 20, 2013 at 06:46:56AM -0600, Eric Blake wrote: > On 09/19/2013 09:48 PM, Jeff Cody wrote: > > For image formats that are not "QEMU native", but supported for > > compatibility, it is useful to verify that an image created with > > the 'gold standard' native tool can be read / written to successfully > > by QEMU. > > > > In addition to testing non-native images, this could also be useful to > > test against image files created by older versions of QEMU. > > > > This provides a directory to store small sample images, for use by > > scripts in tests/qemu-iotests. > > > > The MANIFEST file should be updated when a new image is added to the > > directory, to give some idea about the nature of the image and the > > data store therein. > > > > Image files should be compressed with bzip2. > > Why bzip2? xz beats bzip2 in both compression ratio and decompression > speed; or if you are worried about portability, gzip is present on more > machines. bzip2 will probably be around for some time, but it is no > longer the compression engine of choice. > iotest-dynamic-1G.vhdx compressed with gzip, xv, and bzip2: gzip: 102548 bytes xv: 15892 bytes bzip2: 874 bytes I think bzip2 is particularly well suited for image files with hyper-repetitive consecutive bytes due to its use of RLE. I don't know that all sample images will have data like that, but chances are good many will - and even if they don't, bzip2 is not horrible compared to xz even on normal data. -Jeff