Sometime ago, I encountered a situation where (due to circumstances) production servers were running on old, unsupported hardware. No need to tell you that the customer and the support team were very uncomfortable with this situation. The number one priority was to get the production servers on supported hardware. The organization is also in a process of transformation, a forthcoming project is to migrate to a Windows 2008 R2 platform, new Directory Services etc.
So, it was decided to build a new infrastructure based on VMware vSphere, new servers and a SAN. To resolve priority number one, the advise was to go for a Physical-to-Virtual (P2V) conversion.
The first product that comes into mind is the VMware product, officially “VMware vCenter Converter Standalone”, (from now on, “Converter Standalone”). The official link is here.
Today the VMware Converter is a free product. If you haven’t already done so, register with VMware and you can download the VMware Converter. The VMware Converter is available in these editions: 5.0, 4.3, 4.0.1 and 4.0.
The “Resources” tab leads you to the documentation. The User’s Guide is a comprehensive document that describes every detail about the Converter Standalone and its usage. Chapter 1 also includes an interesting topic on types of Data Cloning Operations. In short, there are 2 options:
- Hot cloning, also called live- or online cloning, which requires the physical server running its operating system during the converting process.
- Cold cloning, also called offline cloning, which requires the physical server not running its operating system. When you cold clone a server, you reboot the source machine using a CD that has its own operating system and the Converter Standalone application on it.
The topic concludes with an Hot and Cold Cloning Comparison.
There is one important caveat , the before mentioned boot CD is not free, in fact you will at least need a vSphere Enterprise license to download it. What you also need to know is that Converter Standalone 4.3 and later do not support cold cloning, you must use the Boot CD of an earlier edition.
An alternative could be the MOA project on http://sanbarrow.com/moa.html which offers a replacement for the VMware Boot CD.
Hot or Cold Cloning?
How do we answer this question? I think it the answer is, “it depends”. Until this project Hot cloning was my favourite method. Very useful is the VMworld Session “VMware Converter 3.0.2. Troubleshooting” which you can download from here.
In this project we had to take into account the following topics:
- Two Windows Domain Controllers should be converted. Best practice is to create VMs and build new Domain Controllers and demote the physical one’s. Unfortunately these Domain Controllers have more roles like file and application server (not best practice, I know). In that case there is only one option: Cold Clone.
Very important, after conversion and booting the virtualized Domain Controller, never, ever reconnect the physical Domain Controller or you will be in great trouble. Read more on this topic in this excellent blog post.
- The physical servers reside in a different VLANs than the management network of the ESXi servers and the vCenter server. Both methods require some modification. Using the hot clone method, requires a modification to allow traffic between VLANs (the network admin does not like). Another option for hot cloning is to reconfigure the switch port for the management VLAN, this also requires changing the IP address of the NIC.
- Another customer requirement was, minimal configuration changes on the physical servers and easy fall back in case the conversion does not succeed.
The final solution was: use the cold clone method, one NIC of the physical server (in most cases a spare NIC) was attached to an available switch port in the management VLAN. This method met the requirements of the customer:
- Minimal configuration changes. No additional software configuration on the server (a hot clone installs an agent during the process). No changes in the network configuration of the physical server.
- Easy fall back, just remove the connection to the NIC used for the conversion, remove the boot CD and reboot the server.
What did we learn?
As always, preparation is important.
- Prepare the extra switch ports used during the conversion.
- Check the NICs in the physical servers, support 1 Gb/s.
- Does the physical servers have a console or remote access card? You will need a keyboard and monitor using a boot CD.
- Does the physical servers have a CD-ROM?
- If your server supports booting from an USB CD-ROM drive, have a drive available.
- Does the drive CD-ROM works fine? One 8 year old drive succeeded to boot the CD after 8 reboots…
- Prepare the Converter Boot CDs.
- On each server, make a note of the network settings. Use these commands.
ipconfig /all > network.txt
route print >> network.txt
- Check the health of the Windows Domain before you start the conversion process. Check again after the conversion of each Domain Controller. For instructions, see this post, or on http://www.petri.co.il
- On the domain controllers, create an extra System State backup, using NTbackup and store locally (In case things go really bad).
During the conversion process
- When the Converter reports that “No OS has been found”, changes are that the RAID controller of the physical server has not been recognized, for instance some Dell SAS controllers.
The good news, a few moments after booting the Boot CD, you can press F6 and add additional drivers. I used an extra USB floppy drive to solve this.
- Does the physical server has a small System drive? During the conversion process make sure every partition will be converted to a separate disk. You can also expand volumes during the conversion process. Do not convert hardware vendor’s management partitions.
- One of the important steps after converting a physical server is to clean up the newly created VM. Especially remove things like RAID management software, Dell Open Manage etc. Kendrick Coleman at http://www.kendrickcoleman.com provides an excellent collection of tools for cleaning, bundled in an .iso image. Upload to your environment, mount the .iso and go. You can find it here.
- Do not panic in case something goes wrong.
To conclude, the Converter Standalone is a very good product for converting physical servers to virtual. Personally, I regret that the Boot CD has been discontinued, especially since the latest version 5.x has some very interesting features, like partition aligning. As always, if you have any questions, please respond. Happy reading.