Just for the Health of It

P2V Tools & Plugins For Virtualisation Projects

P2V, (Physical-To-Virtual), is the acronym that describes the tools and plugins that are available to move images from a physical host to a virtual host.

Lets understand the nomenclature first:

  • ‘Physical’ refers the hardware (computer/server box) environment. This is the ‘traditional’ and most common method of delivering server services / resources to the network.
  • ‘Virtual’ refers to the environment which is created by virtual software, and is able to support / host multiple instances of an operating system/s.

So, if you like, the Physical is, probably, what you have, and the virtual is, probably, where you want to be. How you get there is where the P2V tools and plugins come in.

P2V works by copying the physical state of an installed operating system as an image. If you have used Ghost, or Acronis, you will know what I mean. This image is a compressed file, much like an ISO. It can be stored, or used, whenever it is required. It contains all of the system files, drivers, and so forth, that it needs to make it viable when it is decompressed and installed to another computer or into a virtual machine (environment). Images can also be the entire state of a complete operating system and installed applications. kho thuc pham dong lanh tai ha noi

Imaging an operating system is not new. We have been doing that for years. Most workstation rollouts were done using Ghost images (probably still are). Microsoft refined the technique of operating system deployment when it introduced RIS, Remote Installation Server/Service. Unfortunately, RIS was a bit limited by NIC drivers in many environments and didn’t always work well. RIS takes advantage of DHCP (BootP) and DNS to locate and deliver an operating system to a target machine. P2V does just that. But it goes one step further, it deploys from a standard image taken from a physical computer and places that image into a virtual machine. P2V can also move virtual servers from one Host to another Host, irrespective of the type of hardware that supports either Host.

Virtual Machines represent an environment similar to the old NTVDM (NT Virtual DOS Machine). The NTVDM attempted to create an isolated environment within the architecture of Windows NT, above the Executive Layer. It enabled 16bit (DOS) applications to run within a 32bit environment, it still does in fact. The theory was that if the DOS application crashed, as they were likely to do, it wouldn’t take any other applications or the operating system down with it. The application would crash within the NTVDM and the NTVDM would contain that event within the Win32 subsystem, and not allow it to access the hardware (Microkernel). This didn’t always work as it should, and usually resulted in the infamous BSOD. Fortunately things are becoming a little more stable on the Windows front, and we see less BSODs than we use to.

In a virtualised environment the key to efficiency and success is to be able to easily manage the whole infrastructure without too many reboots and downtime. In a traditional / physical infrastructure, downtime is inevitable when management is implemented effectively. When, in a physical infrastructure, it is required that new servers are installed, old ones decommissioned, and existing servers upgraded or moved around, redeployed etc, downtime will happen, whatever you try to do to avoid it. In that scenario it’s a case of limiting the damage and trying to do the work when the network is ‘quiet’. Virtualisation can enable all of these activities without the excessive downtime. P2V tools are used to create and manage the virtualised enterprise.

P2V enables the moving of pre-made server operating system images, (with applications), from a hardware based environment to a virtual environment. This activity can take place when the network is being used. However, as you are going to squirt a large image around the LAN or across the WAN, it’s a good idea to choose a more quiet period, rather than in the middle of the working day, or when the backup systems fire up.

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