Re: [Qemu-devel] [Nbd] Hibernate and qemu-nbd

[Mark Trumpold <markt@netqa.com>]

On 9/26/13 10:18 PM, "Stefan Hajnoczi" <stefanha@gmail.com> wrote:

>
>Try the qemu-nbd --persistent option.  That should prevent it from
>shutting down when nbd-client is disconnected.
>
>Stefan
>


Hi Stefan,

Sorry for the delay..
I tried the following per your suggestion:

  920  qemu-nbd --persistent -p 2000 /root/qemu/q1.img &
  921  nbd-client -persist localhost 2000 /dev/nbd0
  922  fsck /dev/nbd0
  923  mount /dev/nbd0 /mnt
  924  ls /mnt
  925  umount /dev/nbd0
  ::

  927  echo reboot >/sys/power/disk
  928  echo disk >/sys/power/state
  929  mount /dev/nbd0 /mnt

This seems to work; that is both sides (client and server) persist
after the hibernate cycle.

However, if I don't 'umount' '/dev/nbd0' before the hibernate
cycle, and try to 'ls /mnt' after, the 'ls' hangs indefinitely.

For my real use case we have the root filesystem mounted,
so unmounting is not an option (at least I don't think so).

I also tried remounting readonly, and also 'blockdev --flushbufs ..'
before the hibernate cycle -- either or both did not help.

I had thought about trying a 'chroot' and then a 'umount', but
have not yet tried this.

This one was so close..

Thank you for all your attention on this.

Best Regards,
Mark T.