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
