On Mon, Apr 06, 2020 at 10:48:35AM -0500, Eric Blake wrote: > Side note: ... > >+ (* Although glance can slurp in a stream from stdin, unfortunately > >+ * 'qemu-img convert' cannot write to a stream (although I guess > >+ * it could be implemented at least for raw). Therefore we have > >+ * to write to a temporary file. XXX > >+ *) > >+ List.map (fun (_, ov) -> TargetFile (cachedir // ov.ov_sd)) overlays > > I know this was just code motion, but does the nbdkit streaming > plugin help here?
As Pino said in the other answer, -o glance is obsolete. In more direct answer to your question, the streaming plugin doesn't help. There are two problems: (1) It only works if ‘qemu-img convert’ guarantees to write from start to end without ever going backwards. I don't think this is true even for raw. (2) Because Glance’s sparseness support is broken, it's generally recommended that you use virt-v2v to convert the format to qcow2 when writing to Glance. (Virt-v2v gives you a "free" format conversion because under the hood we use ‘qemu-img convert’ to do the copy.) However qcow2 certainly cannot be written linearly unless Kevin has performed a miracle. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/ _______________________________________________ Libguestfs mailing list [email protected] https://www.redhat.com/mailman/listinfo/libguestfs
