Re: [Devel] Re: [RFC] Virtualization steps

[Bill Davidsen <davidsen@tmr.com>]

Kirill Korotaev wrote:

> Bill,
>
> > > OpenVZ will have live zero downtime migration and suspend/resume 
> > > some time next month.
> > Please clarify. Currently a migration involves:
> > - stopping or suspending the instance
> > - backing up the instance and all of its data
> > - creating an environment for the instance on a new machine
> > - transporting the data to a new machine
> > - installing the instance and all data
> > - starting the instance
>
>
> > If you could just briefly cover how you do each of these steps with zero
> > downtime...
>
>
> it does exactly what you wrote with some minor steps such as 
> networking stop on source and start on destination etc.
>
> So I would detailed it like this:
> - freeze VPS

when the VM stops providing services it's down as far as I'm concerned

> - freeze networking
> - copy VPS data to destination
> - dump VPS
> - copy dump to the destination
> - restore VPS
> - unfreeze VPS

and here is where my service is available again. The server may not know 
it's been down, but the clients will.

> - kill original VPS on source
>
> Moreover, in OpenVZ live migration allows to migrate 32bit VPSs 
> between i686 and x86-64 Linux machines.

I guess you're using "zero downtime" as a marketing term rather than a 
technical term.

--
bill davidsen <davidsen@tmr.com>
 CTO TMR Associates, Inc
 Doing interesting things with small computers since 1979

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