Performing a physical-to-virtual (P2V) conversion is an important step toward virtualizing your infrastructure,...
but it’s not always the easiest. There are some common problems you may encounter during a P2V conversion, no matter which P2V tools or methods you use.
Before you even begin a P2V conversion, problems can crop up. Some legacy hardware simply cannot be emulated in a virtual infrastructure. Performing a P2V migration with a DOS-based accounting package running on 16-bit hardware, for instance, isn’t an option because none of the major virtualization platforms support 16-bit guest OSes.
The P2V conversion may also be compromised if you try to convert servers that require specialized hardware. Once upon a time, it was common for software vendors to use hardware dongles as copy-protection mechanisms. But such devices won’t work in virtualized infrastructure. If your physical server uses USB devices, certain types of SCSI devices or specialized video cards, you may encounter other P2V conversion roadblocks.
Physical servers may experience downtime during a P2V conversion. Some physical-to-virtual conversion tools can perform a P2V migration without taking the server offline until it’s time to switch over to the virtual machine (VM). But before you can use such a utility, the server you’re converting must meet certain requirements.
With Microsoft’s System Center Virtual Machine Manager 2008 R2, for example, the physical server requires a version of Windows that supports a required agent. If you want to keep the physical server online during the P2V conversion, then the server’s OS and applications should also support Windows VSS snapshots. Otherwise, the server must be taken offline during the P2V conversion.
If you want to convert a server that’s running an outdated application, you will also encounter issues. As I explained previously, you may experience downtime if the application doesn’t support Windows VSS, but there’s more to it than that.
An organization once approached me about virtualizing a server that was running a very old application. The server was running a new OS, but only because it had been upgraded with new versions of Windows. The application itself hadn’t been updated in at least 15 years, and it was no longer supported, so I decided to perform a clean installation onto a VM to avoid touching the physical server.
Much to my horror, the only copy of the installation files was on floppy disk. I got my hands on a USB floppy drive, but the virtualization platform didn’t allow guest machines to access USB devices. Ultimately, I had to copy the floppies to a DVD just so I could install the application. I suggest keeping applications up to date so you won’t have trouble converting with P2V tools in the future.
Instead of using P2V tools, you can simply back up the physical server and restore the backup to a VM. This approach to P2V migration sounds simple enough, but it must be done carefully. Depending on the hardware it runs on, Windows uses different hardware abstraction layers (HALs). If you try to restore the VM on hardware with a different HAL than that on the physical server’s hardware, you’ll end up with a blue-screen error. If you use this P2V conversion method, install Windows on the VM and make sure to restore it without overwriting the critical system files.
You may attempt a P2V conversion with a legacy physical server only to discover the machine is plagued with previously undetected disk errors. To prevent this roadblock, run the Chkdsk command against all volumes before the P2V migration.
There’s no guarantee that a P2V conversion will be a success. It’s usually possible to virtualize a server, but some servers simply cannot be virtualized. To get a feel for the P2V conversion process and its potential errors, start by converting the least-critical servers first.
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