On Thu, Feb 2, 2012 at 2:08 PM, Eric Blake <eblake@redhat.com> wrote:
Did you mean for this to go to the list?
Yes, sorry :)
On 02/02/2012 12:04 PM, Paul Lussier wrote:
On Thu, Feb 2, 2012 at 1:52 PM, Eric Blake <eblake@redhat.com> wrote:
On 02/02/2012 11:33 AM, Whit Blauvelt wrote:
Is there a way internal to a KVM VM to know which host it's running on?
No. The ideal hypervisor is one where the guest doesn't even know it is running as a virtual machine. And consider live migration - a guest might not be running on the same host over its lifetime. Therefore, there should be nothing that requires a guest to know which host it is running on.
From a system administration perspective, though, it's imperative to know what physical hosts your VMs are running on. Perhaps the VM itself doesn't know, but the sysadmin should be able to have some means of figuring this out in a dynamic manner, not simply by "keeping track" of where VMs are deployed.
Yes, but that's a different question. It's not the guests' job to know which host they are running on, rather, it's the management app _outside of the guests_ that knows which hosts are running which guests.
What do you mean by "management app", virt-manager, or something else ?
Why do you think you need it? Perhaps if you ask a better question about what you are really trying to solve, we can give a better answer.
Asset tracking, physical host trouble-shooting, etc. If I'm running an environment with 2K physical systems, each of which are running 20+ VMs, and someone reports a problem with vm-23475, it would be really nice to know that I can ask that VM where it is on my network and on what physical hosts. Especially if that VM has been around a while and possibly migrated to/from several physical systems.
That's more a question you should be directing to your management app, not to your guest. Your management app should know which host is currently running vm-23475; you shouldn't have to directly query vm-23475 itself (besides, if you treat guests as untrusted code, you wouldn't want to rely on any answer vm-23475 gave you in the first place).
While I agree with you in principle, my impression is that people are not treating guests as untrusted code, but rather, almost exactly like physical hosts. Perhaps I haven't had the luxury of being in a virtual environment where people are doing things the way they were intended :) -- Paul