On Sat, Mar 04, 2017 at 01:14:39AM -0600, Leroy Tennison wrote: > Is it possible to insert and eject a USB image in kvm/qemu/libvirt or are > the only dynamically changeable devices cdroms and floppies? I've searched > the web and I'm either not looking for the right terms or it's obscure. I > should mention that I'm not talking about a connecting a physical host USB > drive to a guest image, I want to be able to use a qcow image as the source. It depends on what kind of USB device you attach. If you attach a USB hard disk, then to dynamically change the backing store image, you would need to do USB hotunplug+hotplug to remove the "old" drive & add a "new" drive. If you were to attacha USB cdrom, then you have the choice of simply ejecting the media, but can still also do hotunplug+hotplug. > > The context is that I want to be able to revert a VM image back to a prior > state (internal snapshot) when testing but be able to retain some data > without having to go to the effort of transferring it across the network. > I've excluded cdroms as an option because they are read-only (correct me if > I'm wrong on this) and require some effort to (re)build. Floppy drives > appear to be limited to 1.44M which makes sense but is very limiting. Correct wrt cdroms & floppies. > Network mounts (NFS, Samba, etc.) require a server supporting the selected > style of filesystem sharing over the network. I'm not sure I want to find > out what happens to filesystem passthrough when a revert is done (unless > someone knows and it's beneficial). > > I tried creating a partition associated with the VM but not auto-mounted, > even if I unmounted the partition before reverting its state was rolled > back. I possibly could get exotic here by setting the immutable attribute > after unmounting the partition but, again, I'm hoping for something a little > simpler and more straightforward. If there's a workable option I haven't > considered I'm open to that. It sounds like you should want to be using qcow2 internals snapshots to capture memory+disk state, or if you wnt to get more advanced libvirt has APIs to allow fine grained creation of snapshots in standalone files. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :| _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
