Re: [Xen-users] linux stubdom

[Markus Hochholdinger <Markus@xxxxxxxxxxxxxxxxx>]

Hello,

Am 01.02.2013 um 09:56 Uhr schrieb Ian Campbell <Ian.Campbell@xxxxxxxxxx>:
> > > >  Am I missing something?
> > > Migration is a staged process.
> > >      1. First an empty shell domain (with no devices) is created on the
> > >         target host.
> > >      2. Then we copy the memory over, in several iterations, while the
> > >         domain is running on the source host (iterations happen to
> > >         handle the guest dirtying memory as we copy, this is the "live"
> > >         aspect of the migration).
> > >      3. After some iterations of live migration we pause the source
> > >         guest
> > >      4. Now we copy the remaining dirty RAM
> > >      5. Tear down devices on the source host
> > >      6. Setup devices on the target host for the incoming domain
> > >      7. Resume the guest on the target domain
> > >      8. Guest reconnects to new backend
> > > The key point is that the devices are only ever active on either the
> > > source or the target host and never both. The domain is paused during
> > > this final transfer (from #3 until #7) and therefore guest I/O is
> > > quiesced.
> > At what point are scripts like
> >  disk = [ ".., script=myblockscript.sh" ]
> > executed? Would this be between #3 and #7?
> It is part of the device teardown and setup, so it is during #5 and #6
> (strictly I think it is just after #5 and just before #6).
> On xen-devel at the minute there is a patch series under discussion to
> make the script hooks more flexible, in particular adding pre and post
> migrate hooks (called something like #1-#3 and #7-#7) which can pre
> setup bits of the storage stack which are safe to do with the guest
> running but might be slow to initialise (e.g. iSCSI login, but not
> opening the device). I don't think this needs to affect you though.

at least with xm toolstack, block-scripts in /etc/xen/scripts/block-* are 
executed on the destination host (add) before the script (remove) on the 
source host is executed while live migrating a domU.

(I've created the script /etc/xen/scripts/block-md which assembles and stops 
raid1 devices.)

Next, I'll test xl toolstack with this setup.


[..]

-- 
greetings

eMHa

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