Cole Robinson writes: > This series is the first steps to teaching libvirt about qcow2 > data_file support, aka external data files or qcow2 external metadata. > > A bit about the feature: it was added in qemu 4.0. It essentially > creates a two part image file: a qcow2 layer that just tracks the > image metadata, and a separate data file which is stores the VM s/is stores/stores/ > disk contents. AFAICT the driving use case is to keep a fully coherent > raw disk image on disk, and only use qcow2 as an intermediate metadata > layer when necessary, for things like incremental backup support. > > The original qemu patch posting is here: > https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg07496.html > > For testing, you can create a new qcow2+raw data_file image from an > existing image, like: > > qemu-img convert -O qcow2 \ > -o data_file=NEW.raw,data_file_raw=yes > EXISTING.raw NEW.qcow2 What happens if you try to do that in place, i.e. EXISTING==NEW? > > The goal of this series is to teach libvirt enough about this case > so that we can correctly relabel the data_file on VM startup/shutdown. > The main functional changes are > > * Teach storagefile how to parse out data_file from the qcow2 header > * Store the raw string as virStorageSource->externalDataStoreRaw > * Track that as its out virStorageSource in externalDataStore > * dac/selinux relabel externalDataStore as needed > -- Cheers, Christophe de Dinechin (IRC c3d) -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
