Be aware: Converter 5.0 does not (yet) work with vSphere 5.1

Those of you who have just completed a brand new vSphere 5.1 deployment or upgraded your production environment to 5.1 may run into a real show stopper ... once you try to virtualize a physical server into this environment using VMware Converter. Why? Because the current release of VMware Converter (5.0) does not work together with ESXi 5.1 and vCenter Server 5.1! The 5.0 version of the Converter is a bit old now and has not yet been adapted to work with vSphere 5.1. Maybe VMware just forgot that, or was in such a hurry to release vSphere 5.1 that they intentionally neglected Converter compatibility.

If you desperately need to use Converter with vSphere 5.1 *now* then you have the following work arounds available:

1. Use VMware Converter 4.3 (still available here). This version has been reported to work. But keep in mind that this is also unsupported by VMware, and you lose the automatic guest disk alignment feature of Converter 5.0.
2. Deploy an ESXi 5.0 host in your environment. If you do not have spare hardware available then you can also deploy a virtual ESXi 5.0 host and make some NFS or iSCSI storage accessible to it that you can also share with your physical ESXi 5.1 hosts. Then use Converter 5.0 against this virtual ESXi 5.0 server and move the VMs to the physical ESXi 5.1 hosts after conversion (with Storage VMotion).

In both cases you should upgrade the VM's virtual hardware once they arrived on an ESXi 5.1 host.

If the P2V is not super urgent for you then I strongly recommend waiting for the release of Converter 5.0.1 that will be compatible with vSphere 5.1 and eliminate any work arounds needed. According to this forums post we can expect it in a few days. I will update this post once it becomes available.

Update 2012-10-26: VMware Converter has now been released. See this post for more information.