Luke S Crawford wrote:
Ruslan Sivak <russ@xxxxxxxxxx> writes:
running vmware under a xenU guest wouldn't lift any ram limit
imposed by the xen kernel or dom0.
...
The 4GB limit is artificial, and only applies to the vm's started
using their closed source XenSource. The host OS is most likely
CentOS 5, and sees the whole 8GB (although it's not x64, so I'm
guessing they use PAE or something.)
It is PAE.
If it's PAE, then I'm a bit confused, as they advertise it as "*Native
64-bit hypervisor:* Scalability and support for enterprise applications"
I only need 8GB of ram support, and no other features that are offered
in XenStandard, so it seems kind of a waste to pay $1k per server for
that. If another virtualization technology was installed on that OS,
you can get the use of the other 4GB, and if not, I can always run my
apps on Dom0, although I'd prefer to not install too much stuff on
Dom0.
First, The Dom0 OS runs as a guest of the Xen hypervisor- it is just
a guest that happens to have access to the PCI bus as well. The Xen
hypervisor still controls what ram and CPU all domains including the Dom0,
can see; if the xen kernel is limiting you to 4G ram total, that
limit will apply in the Dom0 as well.
Also, you are not going to be able to run a virtualization technology that
uses the hardware virtualization support from within a Xen guest, even
if that Xen guest happens to be the Dom0. The Xen hypervisor
controls access to those instructions.
You can run virtualization technologies that don't require HVM- OpenVZ and
linux vserver will both work fine. Heck, you can do that within an
unprivileged Xen DomU, but that won't help you if you want to run
windows.
Well I have up to 4GB of run windows and I can have the other 4GB for
dom0, so if I can get OpenVZ or linux vserver running on there, I can
use that to run my linux VM's.
Doesn't openVZ require a different kernel? That would replace the Xen
kernel wouldn't it? Or is there a way to custom compile Xen+OpenVZ kernel?
I'm not too familiar with linux vserver, but my guess is you can't run
it in Dom0 either...
Russ
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