[Lxc-users] [CRIU] Do we have a plan to make the checkpoint/restart feature.

Nipun Arora nipun2512 at gmail.com
Wed Dec 4 23:20:02 UTC 2013


Hi Pavel, and Serge

Thanks for the fast response. I understand the limitation. However, I would
like to understand if criu can be used in its current version with lxc.
To allow for criu to work, I've tried the following combinations in lxc
configuration files

lxc.console = none
lxc.tty = 0

I am unable to start lxc using the stand lxc-start command. I am assuming
this is because no consoles have been configured. I've tried starting the
container as a daemon as well. That did not seem to work as well.

Thanks
Nipun

I am fairly new to lxc so I might be doing something wrong


On Wed, Dec 4, 2013 at 1:48 PM, Pavel Emelyanov <xemul at parallels.com> wrote:

> On 12/04/2013 10:12 PM, Serge Hallyn wrote:
> > Quoting Nipun Arora (nipun at cs.columbia.edu):
> >> Hi,
> >>
> >> I've been tryint criu for checkpointing and restart. One of the issues
> is
> >> that criu does not support external console.
> >> I tried setting lxc.console = none, and lxc.tty = 0... but seem to get
> no
> >> progress when I run the following command..
> >>
> >> lxc-create -t ubuntu -n test_lxc -f test_config
> >> lxc-start -n test_lxc
> >>
> >> The config file basically has only the following 2 lines
> >> lxc.console = none
> >> lxc.tty = 0
> >>
> >> Can someone help out in explaining why this is happening?
> >
> > I think it's been explained before - the external console points
> > to a device file sitting in another mount namespace.  criu can't
> > checkpoint that.
>
> Ack.
>
> > Back in the in-kernel checkpoint days, IIRC we allowed such files
> > to be marked as uncheckpointable in the image, and the restart
> > program to fill those fds in with fds it had opened beforehand.
> >
> > Can that be done with crui?
>
> In theory -- yes. IOW -- we need to patch criu to achieve that. I
> planned to make this support using plugins to criu that help dumping
> external mount points. Currently Andrey works on such a plugin for
> external unix sockets, you can find his patches on the list From: avagin at .
>
> Similar thing can be done for external (bind)mounts. Does it make
> sense for you?
>
> > -serge
>
> Thanks,
> Pavel
>
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