On Fri, Mar 27, 2015 at 01:27:39PM -0600, Eric Blake wrote:
Is NBD bi-directional, in that the target can receive write requests at the same time it is sending read requests?
It's unidirectional. It's a very simple protocol - you can't even answer requests out of order: https://github.com/yoe/nbd/blob/master/doc/proto.txt In an ideal world for libguestfs we'd have qemu be the NBD server, with some sort of monitor command like: drive-point-in-time-snapshot device:virtio-disk1 port:1000 id:123 then you'd connect to <qemu-server>:1000 and it'd give you access to the drive at that instant in time until there was a further command to discard the snapshot: drive-discard-point-in-time-snapshot id:123 Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top