Re: [Xen-users] xendomains migrate exclude

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2014-05-19 at 21:53 +0200, Torsten Lehmann wrote:
> hallo,
> 
> >> Can you please verify the following points? (true/false)
> >> 1. VMs migrate on "xendomains stop" if set XENDOMAINS_MIGRATE
> >
> > I think so.
> >
> >> 2. "xendomains" do not using config on_xend_stop/on_xend_start
> >> 3. "on_xend_stop" cannot trigger migration (values:
> >> ignore|shutdown|suspend)
> >
> > I don't know about either of those.
> 
> How to migration without xendomains?

I'm not 100% sure what your question is, but perhaps the answer is that
"xl migrate <domain> <target-host>" is the command to migrate a domain
to another host by hand. (and with xend it was "xm migrate...")

> >
> > Ian.
> >
> >
> 
> So I've played through a few variations.
> new: variant #3
> 
> 5.  variants (part)
> 
>    1. xendomains: migrate if on_xend_stop==migrate
>       - not backwards compatible (migrate if on_xend_stop==ignore)
>    2. xendomains: migrate if on_xend_stop!=shutdown
>       - possible
>    3. xendomains: migrate if on_xend_stop!=shutdown && on_xend_stop!=suspend
>       save if "$on_xend_stop" != "shutdown"
>       - better
> 
> 
> 6. Table variant action
> variant       on_xend_stop    action
> org   ignore  migrate
> org   shutdown        migrate
> org   suspend migrate

is that really correct? seem very broken...

> 1     ignore  undef
> 1     shutdown        migrate
> 1     suspend migrate
> 1     migrate migrate
> 2     ignore  migrate
> 2     shutdown        shutdown
> 2     suspend migrate
> 3     ignore  migrate
> 3     shutdown        shutdown
> 3     suspend save
> 
> I think the best option is variant 3.

ignore=>migrate seems a bit odd. I think it was in general possible to
stop xend without doing anything to the domains (of course you could no
longer manage them, but they would keep running).

> Implementation see [1].
> 
> Should I post it to git?

xend is no longer present in the development tree and won't be in 4.5.
It's not clear to me how strongly related to xend this functionality is,
but it *seems* like it is very closely tied to xend the way xend worked.
In particular the equivalent concept of on_xl_stop doesn't really exist
-- because the model with xl is different and there is a single daemon
per domain rather than one global daemon.

It might still be worth posting your patches for the benefit of other
xend users etc.

Or if you start planning a move to a newer version of Xen which uses xl
and you find that you are missing whatever the equivalent bit of xl
functionality is we can investigate from that angle. (obviously the
sooner in advance of your migration to xl we can do that the better...)

Ian.


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