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Re: [Qemu-devel] [Nbd] Hibernate and qemu-nbd
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [Nbd] Hibernate and qemu-nbd |
Date: |
Thu, 10 Oct 2013 11:15:54 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Oct 04, 2013 at 07:30:45AM -0700, Mark Trumpold wrote:
>
>
> On 9/26/13 10:18 PM, "Stefan Hajnoczi" <address@hidden> 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..
Too bad. I'm sure it's solvable but would require more debugging and
writing qemu-nbd.c and kernel nbd.c fixes. Unfortunately I don't have
time to look into it myself.
Stefan