Hi folks,
Now that CentOS 5 is out with Xen, I can theoretically take better advantage of my nice Intel processor with the virtualization piece than I can with VMware Server.
Ideally what I would like to do is install CentOS 5 as a dom0, then run my existing CentOS 4.x installation as a domU while I figure out how to do other interesting things (like install Solaris 10 and Windows as domU installations).
Does anyone have any links to pages which might show me how to use Xen to run an existing, already-installed CentOS (or RedHat) under Xen as a domU?
Thanks for any links or hints you might have.
On Mon, May 28, 2007 at 11:29:03AM -0400, David Mackintosh wrote:
Hi folks,
Now that CentOS 5 is out with Xen, I can theoretically take better advantage of my nice Intel processor with the virtualization piece than I can with VMware Server.
You can't. Xen's fully virtualized hardware implementation isn't as fast as VMware's. Also, there are no para-virtualized drivers for HDD, lan or video for Windows, as there are in VMware.
Ideally what I would like to do is install CentOS 5 as a dom0, then run my existing CentOS 4.x installation as a domU while I figure out how to do other interesting things (like install Solaris 10 and Windows as domU installations).
CentOS 4 and OpenSolaris as paravirtualized will be much faster than under VMware. But Windows can only run as fully virtualized.
Does anyone have any links to pages which might show me how to use Xen to run an existing, already-installed CentOS (or RedHat) under Xen as a domU?
yum -y install kernel-xenU :)
That should create the initrd and kernel that you can then use in Xen.
Luciano Rocha wrote:
You can't. Xen's fully virtualized hardware implementation isn't as fast as VMware's. Also, there are no para-virtualized drivers for HDD, lan or video for Windows, as there are in VMware.
Do you have any details or stats on this claim that Xen's full-virt isnt as fast as VMware's ? Based on what I've seen Xen's full-virt is actually a fair bit faster than vmware. Besides para-virt on Xen is many many times more efficient than vmware's machine emulation.
On Mon, May 28, 2007 at 05:53:50PM +0100, Karanbir Singh wrote:
Luciano Rocha wrote:
You can't. Xen's fully virtualized hardware implementation isn't as fast as VMware's. Also, there are no para-virtualized drivers for HDD, lan or video for Windows, as there are in VMware.
Do you have any details or stats on this claim that Xen's full-virt isnt as fast as VMware's ?
No, no benchmark. My hardware doesn't support VT, and I haven't been allowed sufficient time for doing proper benchmarks on hardware that do support it.
My opinion is based on what I've read in xen's lists. That current qemu hw emulation and vm implementation requires several trips between dom0 and domU for a *single* request. And some user cases where network throughput is in the *Kbps*.
This isn't the case if you have access to VirtualIron or Xen Enterprise, that provide para-virtualized drivers (for Windows; for Linux there is already source code in the tree).
Based on what I've seen Xen's full-virt is actually a fair bit faster than vmware.
If the bottleneck is CPU or memory, xen will be faster. But I/O will be very slow, compared to VMware (mayben even without vmware drivers installed, as it at least emulates a scsi controller).
Besides para-virt on Xen is many many times more efficient than vmware's machine emulation.
That's true, and I mentioned that in my email.
Also, you can't use VMware under xen (unless in a fully-virtualized guest), but you can use xen under VMware (but don't expect great performance).
On Mon, 28 May 2007 17:53:50 +0100 Karanbir Singh mail-lists@karan.org wrote:
Do you have any details or stats on this claim that Xen's full-virt isnt as fast as VMware's ? Based on what I've seen Xen's full-virt is actually a fair bit faster than vmware. Besides para-virt on Xen is many many times more efficient than vmware's machine emulation.
I recently did some tests, 'completely unscientific', just real world experience. 2 similar servers, Intel Core 2 Duo 2.1Ghz 4MB cache, 4Gb RAM, 2 Sata2 320GB, and I emphasize similar not identical. It was mostly for a database server, for Firefird and IBM DB2.
VMware server was somewhat faster in the disk access, and Xen was somewhat faster as a 'RAM server'. Overall, they were both similar in speed, we chose VMware because drive access was faster.
On Mon, May 28, 2007 at 04:40:09PM +0100, Luciano Rocha wrote:
On Mon, May 28, 2007 at 11:29:03AM -0400, David Mackintosh wrote:
Hi folks,
Now that CentOS 5 is out with Xen, I can theoretically take better advantage of my nice Intel processor with the virtualization piece than I can with VMware Server.
You can't. Xen's fully virtualized hardware implementation isn't as fast as VMware's. Also, there are no para-virtualized drivers for HDD, lan or video for Windows, as there are in VMware.
Well not having paid for VMware ESX, _and_ having a fancy Intel processor with the VT feature, these are not issues.
What might be more intersting would be to compare the paravirtualization abilities of VMware Server with the full virtualization abilities of Xen.
hi David,
David Mackintosh wrote:
Does anyone have any links to pages which might show me how to use Xen to run an existing, already-installed CentOS (or RedHat) under Xen as a domU?
The virtualisation guide included in CentOS is a good place to start. Has most of the info you need and relevant to the tools included in the distro.
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centos＠911networks.com -
David Mackintosh -
Karanbir Singh -
Luciano Rocha