When I got xm pause working, I was quite excited. However, it doesn’t work in all cases. I’ve done some testing to figure out what combination of things cause it to fail.
- Using blktap2 backed disks in the vhd format (vhd-util create -n name -s 1024) xm pause fails. The user-space disk devices are never released, and only a hard reboot will get it to function again.
- Using a different driver for the blktap2, tap:tapdisk:aio, also fails to pause.
- Using phy:/ backed disks, say through LVM works fine. The domU will pause, and resume nicely.
It would seem that there is something not quite ready to be used regarding the blktap2 backend, so I wouldn’t reccomend using it.
I also tried to use the original tap:aio drivers, but I cannot as they don’t seem to exist. I guess I’ll be using the plain old phy:/ drivers for now. That’s not a big deal as I don’t have any second xen machine to do anything fancy that the tap:aio drivers would provide. I guess I should poke on a mailing list or something.