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? -- Matthew Miller ☁☁☁ Fedora Cloud Architect ☁☁☁ <mattdm@xxxxxxxxxxxxxxxxx> -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
