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Date: Tue, 11 Apr 2006 14:38:51 +0400
From: Kirill Korotaev <dev@sw.ru>
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To: Bill Davidsen <davidsen@tmr.com>
CC: Kir Kolyshkin <kir@openvz.org>, akpm@osdl.org,
       Nick Piggin <nickpiggin@yahoo.com.au>, sam@vilain.net,
       linux-kernel@vger.kernel.org,
       "Eric W. Biederman" <ebiederm@xmission.com>, serue@us.ibm.com,
       Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>, herbert@13thfloor.at
Subject: Re: [Devel] Re: [RFC] Virtualization steps
References: <1143228339.19152.91.camel@localhost.localdomain> <200603282029.AA00927@bbb-jz5c7z9hn9y.digitalinfra.co.jp> <4429A17D.2050506@openvz.org> <443151B4.7010401@tmr.com>
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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
- freeze networking
- copy VPS data to destination
- dump VPS
- copy dump to the destination
- restore VPS
- unfreeze VPS
- kill original VPS on source

Moreover, in OpenVZ live migration allows to migrate 32bit VPSs between 
i686 and x86-64 Linux machines.

Thanks,
Kirill