Re: [Xen-users] xm save -c

["Nick Couchman" <Nick.Couchman@xxxxxxxxx>]

Thanks, Todd,
I'm less concerned about the disk and more about Xen being able to do the 
memory save "seamlessly" so that there isn't any pause for the user while the 
save is completed (or at least not near as long as it is now).  The disk would 
be nice, too, although I'm using OCFS2 and not LVM or ZFS for my domUs, so I'm 
not sure how much that would help me.  Any chance it could be implemented with 
Qcow, as well?  VMware does something like this and then quickly changes out 
the disk that the VM sees from the original to the qcow image.

-Nick

>>> On 2008/09/30 at 22:32, "Todd Deshane" <deshantm@xxxxxxxxx> wrote:
On Sat, Sep 27, 2008 at 2:48 PM, Nick Couchman <Nick.Couchman@xxxxxxxxx> wrote:
> I'm tossing around the idea of creating a sort of "VDI" setup with Xen.  One
> thing that I would like to do in this scenario is "checkpoint" the user's VM
> at a certain interval so that if something bad happens they can go right
> back to the latest point time - maybe a half-hour earlier or something like
> that.  I was trying to use "xm save -c <Domain> <File>" to do this, but the
> domain pauses while the contents of memory are saved off to disk.  I was
> wondering if anyone knows of a way to "checkpoint" without pausing the
> domain?  I can't do something like an hourly checkpoint if the domain pauses
> every hour - the users on the domUs would kill me.  Is "seamless
> checkpointing" something that's being developed, something that can be done
> another way, or something I should just give up on now?
>

It is on the TODO list (last updated Jan 08):
http://wiki.xensource.com/xenwiki/XenTodoList 

I think the LVM snapshots should be a good way.

Another idea is to use a ZFS domain.

I'll look into this more soon.

A quick google search and remembering back to a previous Xen summit,
there have been attempts. I don't know the status of them though.

Feel free to float around ideas and discussion about this type of thing
on the xen-research list.

We should also do a better search of the summits and mailing lists
to see what has been done and also check roadmaps and ask xen-
devel if anybody is working on it.

Cheers,
Todd

-- 
Todd Deshane
http://todddeshane.net 
check out our book: http://runningxen.com



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