Comment 147 for bug 1505564

Except that what happens on the compute nodes is that, when creating an instance, nova attaches the image with qemu-nbd (say to /dev/nbd0), and then tries to mount /dev/nbd0 somewhere, except that doesn't work because the image has partitions, and so the root device is actually on /dev/nbd0p1. So the "mount" commands return an error, and nova then detaches the image with qemu-nbd -d.

Overall, as far as nova logs show, there is 0 write on the nbd device and very few reads (probably just the MBR ?). Could that still cause inflight I/O when qemu-nbd -d is ran ?

I'll happily test your kernel PPA, but as far as I can see, you don't mention where it actually is :)

Thanks !