WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

Re: [Xen-devel] XEN migration architecture question

To: Eric Tessler <maiden1134@xxxxxxxxx>
Subject: Re: [Xen-devel] XEN migration architecture question
From: Andrew Warfield <andrew.warfield@xxxxxxxxx>
Date: Thu, 20 Jan 2005 21:16:42 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxxx
Delivery-date: Thu, 20 Jan 2005 21:17:58 +0000
Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:references; b=dqK+zq8NhTBdSRko4q+lKRsUX3ZNfa0vHSMwQ5kCzB1t+gIajrw1SiVmKoM8y5QxV7xPpOUONKFfBrnLLSuWLyio/R1zWxJmuVtqI9ILcApdaxZ6RC9c7w0yeUyUixyNltFdKFJ1FY7Xyw8mcO+wBlXwNkjifgN3reJLOxGllgo=
Envelope-to: xen+James.Bulpin@xxxxxxxxxxxx
In-reply-to: <20050120204440.26397.qmail@xxxxxxxxxxxxxxxxxxxxxxx>
List-archive: <http://sourceforge.net/mailarchive/forum.php?forum=xen-devel>
List-help: <mailto:xen-devel-request@lists.sourceforge.net?subject=help>
List-id: List for Xen developers <xen-devel.lists.sourceforge.net>
List-post: <mailto:xen-devel@lists.sourceforge.net>
List-subscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=subscribe>
List-unsubscribe: <https://lists.sourceforge.net/lists/listinfo/xen-devel>, <mailto:xen-devel-request@lists.sourceforge.net?subject=unsubscribe>
References: <20050120204440.26397.qmail@xxxxxxxxxxxxxxxxxxxxxxx>
Reply-to: andrew.warfield@xxxxxxxxxxxx
Sender: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx
Hi Eric,

Migration will handle network interfaces and *network attached* block
devices, even under i/o load.  For network devices, an ARP
advertisement is sent indicating the new location of the VM.  We've
tested this a fair bit in cluster environments and are able to migrate
heavily i/o loaded servers very fast.  You may see a few dropped
packets, but TCP will take care of that.  Block devices will see the
backend disconnect when they are suspended, and should reconnect and
reissue any outstanding requests when they resume.

In our migration tests, we generally use network storage.  One
approach that seems to work pretty well is to import GNBD mounts in
domain 0 and export them to the migrating domains --
/dev/gnbd/my-dom-disk will have relevance on both ends of the
migration.

Migration does not currently have explicit support for local block
devices.  It is possible to do, for instance using the block tap to
tunnel the request stream over TCP between the two hosts, it just
isn't clear that it's all that useful -- most people seem to want to
use migration to offload a running VM completely.

hth,
andy.

On Thu, 20 Jan 2005 12:44:40 -0800 (PST), Eric Tessler
<maiden1134@xxxxxxxxx> wrote:
> I have an important question about XEN's migation operation related to the
> XEN block and network back/front drivers.  If I migrate a domain from one
> machine to another in the middle of heavy disk/network activity, what
> happnens to the back/front end XEN drivers? (I see they have suspend/resume
> operations but I don't believe they are being used)  I see that the front
> end drivers are passing machine addresses to the back-end drivers - are
> these pointers somehow still valid when a domain is moved to another
> machine?  Shouldn't the drivers wait until there is no I/O activity before
> being migrated? 
>   
> Thanks, 
> Eric
> 
>  ________________________________
> Do you Yahoo!?
>  Yahoo! Search presents - Jib Jab's 'Second Term' 
> 
>


-------------------------------------------------------
This SF.Net email is sponsored by: IntelliVIEW -- Interactive Reporting
Tool for open source databases. Create drag-&-drop reports. Save time
by over 75%! Publish reports on the web. Export to DOC, XLS, RTF, etc.
Download a FREE copy at http://www.intelliview.com/go/osdn_nl
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel