On Mon, Jul 15, 2013 at 6:04 PM, Matthew Miller <mattdm@xxxxxxxxxxxxxxxxx> wrote: > On Mon, Jul 15, 2013 at 01:21:27PM +0100, Richard W.M. Jones wrote: >> > Is the compressed image still seekable? If yes, that constrains the >> > window/block size and limits the gains from switching compressors. >> Dan's answer covered one aspect of this: are qcow2 compressed >> images seekable, answer: yes, of course! >> But there's another answer for xz images. Are these seekable? >> Yes. Surprisingly. I've written the code for it: >> https://rwmj.wordpress.com/2013/06/24/xz-plugin-for-nbdkit/#content >> *However* you have to prepare the xz images correctly for this to >> happen (using the --block-size argument, see blog posting above). >> Images created using standard xz parameters won't be seekable. I >> suggest it's a good idea that we do that for the cloud images, since >> the penalty is only about 1% and it makes them a lot more useful if >> you can use them without uncompressing them. > > Interesting. This would probably be a RFE against appliance-tools (and in > the future ImageFactory), for producing raw.xz images in that way. > > Or, bigger picture, maybe a future qcow2 format could support this natively? Confused. Support what? Your comment above indicates that compressed qcow2 images are seekable already. ...Juerg > > -- > Matthew Miller ☁☁☁ Fedora Cloud Architect ☁☁☁ <mattdm@xxxxxxxxxxxxxxxxx> > -- > devel mailing list > devel@xxxxxxxxxxxxxxxxxxxxxxx > https://admin.fedoraproject.org/mailman/listinfo/devel -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
