Migration will cause the virtual machine’s configuration to be modified
Filed under: VMware
When live migrating from ESX 3.0.2 to ESX 3.5 VMware gives an error:”Migration will cause the virtual machine’s configuration to be modified, to preserve the CPU feature requirements for its guest OS.” This error indicates that the .vmx file is about to be changed.
In my case VMware added the following bit:
cpuid.1.eax = “xxxx————xx————–”
cpuid.1.ecx = “——–R–RR——————-”
cpuid.1.edx = “—————————T—-”
cpuid.80000001.eax.amd = “xxxx————xx————–”
cpuid.80000001.ecx.amd = “—————————-0—”
cpuid.80000001.edx = “——————–H———–”
cpuid.80000001.edx.amd = “—–R————–H——T—-”
This CPU masking surprised me because both Servers are completely the same. Than again ESX 3.5 contains Paravirtualization and Virtualized MMU, and I can image that this functionality is exposed to the VCPU and doesn’t need to be exposed in ESX 3.0.2. Anyone else any thoughts on this?
January 8th, 2008 at 00:37
I am looking at the same error tonight using VMotion between 3.0.1 and 3.0.2 identical servers. They have identical hardware for VMotion specifically, and this error surprised me.
Any thoughts on 3.0.1 -> 3.0.2 with this error, or any further information on 3.0.2 -> 3.0.5 with this error?
January 23rd, 2008 at 04:07
I ran into the exact same problem as well. It occurs for me during both Cold and Live Migration. That paravirtualization in ESX 3.5 is causing this issue is a good assumption, although having trouble finding it in any documentation. A good sign of this is the fact that my Windows VM left the CPU flags all empty, as previously with ESX 3.0.2, but it changes for all my Linux ones.
Another issue I am having is that some of my RHEL 4 (32-bit) virtual machines fail to boot, giving the error message “Your CPU does not support long mode. Use a 32bit distribution”. I believe this might be because some of my linux VMs were stored on an AMD server with ESX 3.0.1 and I am moving to an Intel Server with 3.5.
I would write more but I am still trying to figure this one out. From what I can see is that you must upgrade AMD and Intel hosts to the same version (in this case ESX 3.5) or else Cold migrations will fail or the OS won’t boot.
January 23rd, 2008 at 22:42
Problem solved. For some reason my Virtual Machines were labeled as 32-bit OS, when actually they had a 64-bit OS installed. This still creates a warning however when you migrade from 3.0.2 to 3.5. I believe this is neccessary because of the changes to ESX in order for paravirtualization to occur.
I have found out that when in doubt reset the advanced CPU configs to default. Keep in mind that the warning messages will reappear if you migrage accross different versions of ESX again.
January 23rd, 2008 at 23:20
That’s weird. But resetting is fine indeed if you don’t cross migrate… In noticed the same.
March 31st, 2008 at 16:54
Hey folks, I ran into this same problem migrating 3.0.2 guests to 3.5. In my case, when 3.5 was installed, it apparently changed the CPU description from “Dual-Core AMD Opteron(tm) Processor 8220 SE” to “Dual-Core AMD Opteron(tm) Processor 8220″. It may be unrelated as my 3.5 host was a new server. After I upgrade one of my existing 3.0.2’s to 3.5, we’ll see if it modifies the CPU type again.
Cheers