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[Xen-devel] Hacking XenEnterprise / Please Help
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 XP2. 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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