More work on Livebackup for qemu/qemu-kvm

[Jagane Sundar <jagane@sundar.org>]

Hello All,

I have made more progress on the proposed Livebackup feature
for qemu and qemu-kvm.

Based on Jes' feedback, I have switched over to using command
line parameters instead of specific named files. So, a typical
command line looks like this:

# ./x86_64-softmmu/qemu-system-x86_64 -drive \
file=/dev/kvm_vol_group/kvm_root_part,boot=on,if=virtio,livebackup=on \
-drive file=/dev/kvm_vol_group/kvm_disk1,if=virtio,livebackup=on \
-m 512 -net nic,model=virtio,macaddr=52:54:00:00:00:01 \
-net tap,ifname=tap0,script=no,downscript=no \
-vnc 0.0.0.0:1000 -usb -usbdevice tablet \
-livebackup_dir /root/kvm/livebackup -livebackup_port 7900

Note the new option livebackup=on in the drive parameters, and
the two new parameters -livebackup_dir and -livebackup_port

Here's my strategy for rigorous testing of this new code:
I have created two virtual disks in LVM logical volumes, and
added code in qemu livebackup to create a LVM snapshot as
soon as livebackup_client connects to qemu and creates a
livebackup snapshot. Then I binary compare the livebackup
backed up version of the virtual disk image with the
LVM snapshot that was created by using 'cmp'.
The backup images are a bit for bit match!

As always, all information is available at:

http://wiki.qemu.org/Features/Livebackup

I have also sent in my application to make a presentation at
the qemu forum 2011.

In the meantime, I invite feedback on livebackup.
Specifically, I am interested in scrutiny of my testing
methodology.

Also, I plan to add encryption (probably SSL) to the
livebackup TCP connection, and some form of authentication.

Any thoughts, feedback?

Thanks,
Jagane