[Xen-devel] Hacking XenEnterprise / Please Help

[Jim Burnes <jvburnes@xxxxxxxxx>]

Hello everyone,

My company would very much like to use Xen for the big virtualization  
pipeline that were putting together, but we seem to be starved for  
information.
We need the following features in Xen and we're trying to figure out  
the best way to acquire them.
1. Full virtualization of Windows XP
2. Shared Windows boot image with copy-on-write backing storage after  
boot.
3. Ability to shut down a Windows VM and examine the copy-on-write  
file store for data written to the drive.
4. High-performance hyper-virtualized Windows drivers

Our Problem

The most direct solutions to this problem seems to be:

1. XenEnterprise with it's  hyper-virtualized Windows drivers and  
using QCOW files for copy-on-write file store.
Except my experimentation with 3.1.0 last week showed me that there's  
a bug that prevents blk:tap I/O (which qcow uses) from working  
correctly with fully virtualized domains. I did see the patch and  
would be willing to use it against the 3.1.0 source tree except that  
I don't know if I can even make that drastic of a modification to a  
XenEnterprise install.
The other XenEnterprise possibility is to bypass blk:tap and simply  
use LVM snapshots as copy-on-write images.  This works on RHEL 5, but  
XenEnterprise didn't have a required kernel feature enabled to allow  
it.  That means I would need to modify the XenEnterprise kernel to  
enable the feature or go back and hack the version of Xen to allow  
blk:tap.
In either case, it's a significant modification of a turnkey package.

2. RHEL 5/Centos 5 with the updated XenSource 3.1.0 RPMs.

I had this running pretty well.  The device mapper in the XenSource  
3.1.0 kernel for RHEL 5 allowed LVM snapshot copy-on-writes and I  
could probably use the blk:tap patch if I didn't mind recompiling the  
Xen kernel.
Unfortunately we can't use the hypervirtualized windows drivers  
unless we're running XenEnterprise.
---

So.... we're between a rock and a hard place.  We need high- 
performance copy-on-write Windows virtualization.   XenSource makes  
it impossible to use the hypervirtualized windows drivers in anything  
but XenEnterprise, but they restrict the XenEnterprise kernel to the  
feature set that they deem necessary and which falls short of our needs.
I wouldn't mind modifying XenEnterprise in some way, but I fear that  
the XenEnterprise kernel modifications are closed, or our changes  
wouldn't be supported.
If an *Engineer at XenSource* could refer this to the correct sales/ 
pre-sales engineering people I would greatly appreciate it --- we're  
running out of time and this could be a huge and high-profile Xen  
installation.    I've already contacted front-line sales in  
California and they seem to want to hand us off to third-party  
consulting companies.
Perhaps we could license the windows drivers for use under RHEL/Centos?

We have no one to contact other than engineers we've chatted with at  
XenSource through this mailing list.  Otherwise, discussing this  
issue with front-line sales people is highly unproductive.
*HINT* This is your chance to win business from VMWare.

Any help greatly appreciated...

Regards,

Jim Burnes
jvburnes@xxxxxxxxx









 

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