Dom0 restartability

Dom0 restartability

[Subbiah Kandasamy (skandasa)]

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In today's Xen summit I heard there is some work done on the
restartability of dom0. Any pointers to what has been done and what is
pending and the patches ?.

Thanks,

-Subbiah.


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Re: Dom0 restartability

[Pasi Kärkkäinen]

On Thu, Apr 29, 2010 at 04:05:13PM -0700, Subbiah Kandasamy (skandasa) wrote:
>    In today's Xen summit I heard there is some work done on the
>    restartability of dom0. Any pointers to what has been done and what is
>    pending and the patches ?.
> 

Restarting dom0 requires for example moving xenstored out of dom0..
so you don't lose the database when you restart dom0.

-- Pasi

RE: Dom0 restartability

[Subbiah Kandasamy (skandasa)]

Thanks Pasi, I am sure there are other things as well. I am looking for any pointers listing the work done in that area.

Thanks,
-SK.

-----Original Message-----
From: Pasi Kärkkäinen [mailto:pasik@iki.fi] 
Sent: Thursday, April 29, 2010 5:34 PM
To: Subbiah Kandasamy (skandasa)
Cc: xen-devel@lists.xensource.com
Subject: Re: [Xen-devel] Dom0 restartability

On Thu, Apr 29, 2010 at 04:05:13PM -0700, Subbiah Kandasamy (skandasa) wrote:
>    In today's Xen summit I heard there is some work done on the
>    restartability of dom0. Any pointers to what has been done and what is
>    pending and the patches ?.
> 

Restarting dom0 requires for example moving xenstored out of dom0..
so you don't lose the database when you restart dom0.

-- Pasi

Re: Dom0 restartability

[Charlie Smurthwaite]

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Am I correct in believing that the majority of IO for all domains passes
through the DOM-0 kernel? I would think that a huge number of IO drivers
would need to move into Xen in order to allow this without severe IO
disruption. Are there methods of disk / network IO that do not rely on
DOM-0?

Charlie


On 30 April 2010 17:19, Subbiah Kandasamy (skandasa) <skandasa@cisco.com>wrote:

> Thanks Pasi, I am sure there are other things as well. I am looking for any
> pointers listing the work done in that area.
>
> Thanks,
> -SK.
>
> -----Original Message-----
> From: Pasi Kärkkäinen [mailto:pasik@iki.fi]
> Sent: Thursday, April 29, 2010 5:34 PM
> To: Subbiah Kandasamy (skandasa)
> Cc: xen-devel@lists.xensource.com
> Subject: Re: [Xen-devel] Dom0 restartability
>
> On Thu, Apr 29, 2010 at 04:05:13PM -0700, Subbiah Kandasamy (skandasa)
> wrote:
> >    In today's Xen summit I heard there is some work done on the
> >    restartability of dom0. Any pointers to what has been done and what is
> >    pending and the patches ?.
> >
>
> Restarting dom0 requires for example moving xenstored out of dom0..
> so you don't lose the database when you restart dom0.
>
> -- Pasi
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>

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RE: Dom0 restartability

[Subbiah Kandasamy (skandasa)]

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Assuming the applications can tolerate EAGAIN errors and the guest VM's front end keep returning EAGAIN for the period of dom0 going down and coming back up, the drivers don't need to move to Xen/other domain. Also if we have a driver domain which I understand is restartable, how is the pending IO handled ?.

 

Thanks,

-SK.

 

From: Charlie Smurthwaite [mailto:charlie@atechmedia.com] 
Sent: Friday, April 30, 2010 9:55 AM
To: Subbiah Kandasamy (skandasa)
Cc: Pasi Kärkkäinen; xen-devel@lists.xensource.com
Subject: Re: [Xen-devel] Dom0 restartability

 

Am I correct in believing that the majority of IO for all domains passes through the DOM-0 kernel? I would think that a huge number of IO drivers would need to move into Xen in order to allow this without severe IO disruption. Are there methods of disk / network IO that do not rely on DOM-0?

Charlie



On 30 April 2010 17:19, Subbiah Kandasamy (skandasa) <skandasa@cisco.com> wrote:

Thanks Pasi, I am sure there are other things as well. I am looking for any pointers listing the work done in that area.

Thanks,
-SK.


-----Original Message-----
From: Pasi Kärkkäinen [mailto:pasik@iki.fi]
Sent: Thursday, April 29, 2010 5:34 PM
To: Subbiah Kandasamy (skandasa)
Cc: xen-devel@lists.xensource.com
Subject: Re: [Xen-devel] Dom0 restartability

On Thu, Apr 29, 2010 at 04:05:13PM -0700, Subbiah Kandasamy (skandasa) wrote:
>    In today's Xen summit I heard there is some work done on the
>    restartability of dom0. Any pointers to what has been done and what is
>    pending and the patches ?.
>

Restarting dom0 requires for example moving xenstored out of dom0..
so you don't lose the database when you restart dom0.

-- Pasi


_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

 


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Re: Dom0 restartability

[Pasi Kärkkäinen]

On Fri, Apr 30, 2010 at 05:54:37PM +0100, Charlie Smurthwaite wrote:
>    Am I correct in believing that the majority of IO for all domains passes
>    through the DOM-0 kernel?
>

Yes, at the moment dom0 is usually taking care of all the disk/network IO for the guests,
aka disk and network backend drivers are in dom0.

> I would think that a huge number of IO drivers
>    would need to move into Xen in order to allow this without severe IO
>    disruption. Are there methods of disk / network IO that do not rely on
>    DOM-0?
> 

Yeah, you can use 'Driver domains', to have the disk/net backends in a separate guest.
I don't think it makes any sense to have disk/net drivers in Xen hypervisor.
It's much easier to run Linux dom0 or Driver Domain to serve the disk/net IO.

-- Pasi

>    Charlie
> 
>    On 30 April 2010 17:19, Subbiah Kandasamy (skandasa)
>    <[1]skandasa@cisco.com> wrote:
> 
>      Thanks Pasi, I am sure there are other things as well. I am looking for
>      any pointers listing the work done in that area.
> 
>      Thanks,
>      -SK.
>      -----Original Message-----
>      From: Pasi Kärkkäinen [mailto:[2]pasik@iki.fi]
>      Sent: Thursday, April 29, 2010 5:34 PM
>      To: Subbiah Kandasamy (skandasa)
>      Cc: [3]xen-devel@lists.xensource.com
>      Subject: Re: [Xen-devel] Dom0 restartability
> 
>      On Thu, Apr 29, 2010 at 04:05:13PM -0700, Subbiah Kandasamy (skandasa)
>      wrote:
>      >    In today's Xen summit I heard there is some work done on the
>      >    restartability of dom0. Any pointers to what has been done and what
>      is
>      >    pending and the patches ?.
>      >
> 
>      Restarting dom0 requires for example moving xenstored out of dom0..
>      so you don't lose the database when you restart dom0.
> 
>      -- Pasi
> 
>      _______________________________________________
>      Xen-devel mailing list
>      [4]Xen-devel@lists.xensource.com
>      [5]http://lists.xensource.com/xen-devel
> 
> References
> 
>    Visible links
>    1. mailto:skandasa@cisco.com
>    2. mailto:pasik@iki.fi
>    3. mailto:xen-devel@lists.xensource.com
>    4. mailto:Xen-devel@lists.xensource.com
>    5. http://lists.xensource.com/xen-devel