Luke S Crawford wrote: > Ruslan Sivak <russ at vshift.com> 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