Even if you select the Show Hidden Devices option in Device Manager you will not see the old hardware devices as it only displays non-Plug and Play devices that are actually present in the system. Devices that were previously installed but are not currently present in the server are not displayed. What you need to do to display them is to set an environment variable before you launch the Device Manager application.

You might be wondering why you should even remove them in the first place. There are two reasons. The first is that it can cause conflicts when you attempt to assign IP addresses to any new network adapters that are discovered. This is because the old network adapters are still configured on the server and still have their original IP addresses even though they are not physically present. You will not see them, however, when you go in to your network connections, and if you attempt to assign the new network adapter the same IP address as the old ones you will get an IP conflict error message. To resolve this you need to remove the old non-present adapters which will release the IP addresses assigned to them. Microsoft has a KB article that provides more detail on this.

The second reason you want to remove them is that the old non-present device drivers still consume server resources even though the devices are no longer physically present. The resource usage is minimal but when you have multiple virtual machines (VMs) running on a single physical server the resources that are wasted can add up. Fortunately removing those pesky old devices is fairly easy, just follow these steps:

1. Open a Windows command prompt and type the following:

set devmgr_show_nonpresent_devices=1 

This sets an environment variable that tells the device manager to show all non-present devices.

2. At the same command prompt, type

 devmgmt.msc

…which launches the device manager application. Do not try and launch it through the graphical user interface (GUI) instead as the environment variable set in step one only applies to commands run inside the command prompt.

3. Once the device manager window opens, select View from the top menu, and then Show Hidden Devices.

4. If you expand the device categories you will see both present and non-present devices. The non-present devices are shown by the grayed-out icons next to the device names. You can remove them by right-clicking on them and selecting Uninstall. Unfortunately you have to do this one by one as you can not select multiple devices. Click OK at the warning message that appears. If you accidentally delete a device that is present, don’t panic — once you reboot, Windows will automatically install the device driver for it again.

As an example of how many non-present devices there are after a P2V, I removed over 60 of them from a VM that came from an HP DL360 server, as you can see in the images below.

The process of removing these devices can be tedious and time-consuming, especially if you have many servers to do, but is worth doing so your new virtual servers are clean and don’t carry over remnants from their previous hardware. Fortunately there is a way to automate this process; Mike Laverick has created some great scripts that will automate the cleanup of old hardware after a conversion, which are available here.

Converting a physical machine into an ESXi virtual machine works best when you use the latest version of VMware Converter, version 3.0.3. While prior releases, such as 3.0.2 had support for ESXi, it has improved greatly with the updated 3.0.3 release. ESXi has a more updated version as well, version 3.5 Update 3. Likewise, if you are using PlateSpin’s PowerConvert or Vizioncore’s vConverter, you should make sure the version you are using supports ESXi as a target.

For most situations, converting machines to an ESXi host is not a big deal. The only practice issue that you may encounter would be the destination log-in selection of the converted virtual machine. Like many administrators, I have frequently used vCenter as the destination. If vCenter is not present in ESXi, ESXI will use the host as the destination log-in. The figure below shows the log-in:

Performing P2V conversions directly to ESX or ESXi hosts (no vCenter credentials) will use the local password to authenticate, and root is the default credential for ESXi. Beyond that, vCenter Converter converts machines to ESXi host nicely. Guest conversions can be placed in resource pools if set up on the host, as well as selected storage on VMFS volumes that are iSCSI, local,or fibre channel SAN. More information on vCenter Converter can be found on the VMware website.

I found that some of the device drivers that were loaded in the Windows guest operating system even after all driver software was removed. Further, after the P2V conversion the hardware would not be enumerated in the hardware inventory because it was not present. This particular system had SAN connectivity before, and the drivers related to the fibre channel interface were causing me concern related to disk access, and a lot of errors in the local log. On the VMware virtual machine, the driver installed by VMware Tools provides all of the required disk access and I needed to stop this physical system hardware driver from filling up the error log.

The driver was listed in the Non-Plug and Play Drivers section of the Windows device manager. To view this section, be sure to view the hidden devices in the MMC snap-in for Windows Server 2003 systems. The figure below shows this area of Windows:

Once I identified the driver that was causing the issue, it was quite easy to disable the device. On subsequent boots, the offending process did not fill the Windows logs up with the errors related to the device not being present.