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[Xen-devel] Re: new IO layer, dev expoting and my plans for using xen. (

To: "Brian Wolfe" <brianw@xxxxxxxxxxxx>
Subject: [Xen-devel] Re: new IO layer, dev expoting and my plans for using xen. (WAS: Tiny Patch)
From: Ian Pratt <Ian.Pratt@xxxxxxxxxxxx>
Date: Fri, 09 Apr 2004 10:09:04 +0100
Cc: "Ian Pratt" <Ian.Pratt@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxxx, Ian.Pratt@xxxxxxxxxxxx
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> *nod* I'd gathered as much from the list archives.
> Adam filled me in with his take of the plans for the new IO stuff. xen
> itself won't handle the hardware except for the memory, cpu, and access
> permissions. To use a device, you would launch a privileged xenolinux
> kernel and share the devices it has found to the other xenolinux
> instances. Does this sound about right?

Yep, that's how it will work. 

In high availability situations you might want to have a seperate
xenolinux instance to drive each device or class of device. The
plan is to be able to 'live restart' such driver domains if they
fault or otherwise fail.
> The idea is to actually implement a system that scales the resources
> across a cluster setup on an as needed basis. Sort of how apache launches
> threads, and reaps threads based on load. My hope is this will lower the
> need for large multicpu servers to simpler (cheaper) dual, or single cpu
> servers and add in fault tolerance without a complex HA type setup that is
> commonly used now with heartbeat cables and all the interlinking mess (IBM
> HACMP background makes me think that there HAS to be a better way).
> If I am correct in my thinking that xen would be an ideal platform due to
> it's extremely low overhead and remote manageability (coupled with
> xenoboot for loading xenolinux images), I'd effectively have "grid
> computing"(or whatever each company wants to call this stuff.;)
> ). 

Yep, Xen should be great for this kind of application. I should
have checked my live migration stuff in to xeno-unstable in a few
days, which will allow you to load balance by migrating domains
across a cluster without stopping them.

> BTW, if anyone here uses Debian, I'm working on updating Adam's xen
> packages of xen 1.2 to create nightly builds of xen-unstable. 

Cool!  I'm really must bite the bullet and make the switch to debian...


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