[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-users] 32-bit OS images



Mainly I'm thinking of expandability - passing through your NICs to your domU directly means that each NIC can only be connected to one domU - and ease of configuration - passing through NICs means messing around with PCI settings, matching the right PCI bus identifier to the right NIC port, etc.
 
If you're testing performance of passthrough vs. bridge, I can see why you'd want to do that.  I've got three servers set up to run a bunch of domUs (I have probably 30 running on 3 physical servers right now) and I need VLAN support plus network aggregation.  All of this is easier to do in the dom0 and create a bunch of bridges that the domUs can connect to.  Very similar to the way VMware's ESX does things.  My servers are also 1U servers, so I don't have a lot of room to expand PCIe cards or anything like that - I have to make the most of the small amount of space given.
 
-Nick

>>> On 2008/04/24 at 16:54, Asim <linkasim@xxxxxxxxx> wrote:
Thanks Nick for all the information. Yes I want to do some performance
measurements
on pass-through I/O (and bridge I/O). So I just want one DomU. I guess
thats two NICs
one for each Dom*. Apart from lack of migration support, what are the
other disadvantages?

Also, how do i do this? Do i need to hide the PCI from Dom0 and add it
using network-attach script?

-Asim



On Thu, Apr 24, 2008 at 3:50 PM, Nick Couchman <Nick.Couchman@xxxxxxxxx> wrote:
>
>
> What is your reason for wanting to do passthrough I/O?  The only really good
> reason I can think of for it is that you have an application that requires
> very high throughput and extremely low latency.  Otherwise the bridge should
> be fine, and I can think of several reasons why you don't want to use
> passthrough I/O.  One of which is the one you mentioned - migration will be
> worthless because your domUs will be hardware dependent.
>
>
> So, if you're still insistent upon doing passthrough I/O, then, yes, you'll
> need one network card for every domU you have running.
>
>
> -Nick
>
>
>
> >>> On Thu, Apr 24, 2008 at  2:39 PM, Asim <linkasim@xxxxxxxxx> wrote:
>
>
>
>
>
>
> >  2) You don't want to do direct NIC access to a domU, you want to use a
> > bridge.  By default XEN creates a bridge (can't remember what they're
> > calling it these days) that bridges eth0 to all of your domUs.  This
> should
> > allow you to use your single network card with as many domUs as you have
> on
> > your system.
> >
> >
>
> I want to do passthrough I/O for my specific needs and not use virbr0.
> I believe
> this will also disable migration if am not wrong? So, to do a direct NIC
> access
> I think I should hide this PCI from Domain-0, so will need a second
> additional
> NIC?
>
> -Asim
>
>
>
> ________________________________
> This e-mail may contain confidential and privileged material for the sole
> use of the intended recipient. If this email is not intended for you, or you
> are not responsible for the delivery of this message to the intended
> recipient, please note that this message may contain SEAKR Engineering
> (SEAKR) Privileged/Proprietary Information. In such a case, you are strictly
> prohibited from downloading, photocopying, distributing or otherwise using
> this message, its contents or attachments in any way. If you have received
> this message in error, please notify us immediately by replying to this
> e-mail and delete the message from your mailbox. Information contained in
> this message that does not relate to the business of SEAKR is neither
> endorsed by nor attributable to SEAKR.
>
>


This e-mail may contain confidential and privileged material for the sole use of the intended recipient. If this email is not intended for you, or you are not responsible for the delivery of this message to the intended recipient, please note that this message may contain SEAKR Engineering (SEAKR) Privileged/Proprietary Information. In such a case, you are strictly prohibited from downloading, photocopying, distributing or otherwise using this message, its contents or attachments in any way. If you have received this message in error, please notify us immediately by replying to this e-mail and delete the message from your mailbox. Information contained in this message that does not relate to the business of SEAKR is neither endorsed by nor attributable to SEAKR.

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

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.