Tools such as PlateSpin Migrate or vContinuum will save the data gathered from the physical machine as an image, which then gets reinstalled by a hypervisor on a VM.
Data migrated in P2V includes an OS, applications, programs and data from a computer's main hard disk to a VM, or a disk partition. The end result of a P2V migration is a VM with the same data, applications and system configurations as the physical server being virtualized.
P2V enables developers to transfer their physical environment into a digital one, using less hardware and physical space, while giving developers the advantages of VMs, such as more flexibility since VMs can run on multiple platforms.
How physical to virtual works
Before utilizing P2V, one must first determine how many resources a new VM will consume based on how many resources the physical system uses. This is done to determine whether the host VM contains the resources required to host the virtualized platform. Determining resource consumption can be accomplished by utilizing performance monitoring tools, such as Nagios or Zabbix. Information such as memory, disk space or processor load can give insight on a server's current resource consumption and what that resource consumption would look like in a VM.
A P2V tool will save a physical machine's state as an image. This means the data that makes up a physical server or system is electronically copied, similar in concept to how a Docker container saves data by creating an image. The image is installed by a hypervisor in the specified storage space. A person or hypervisor can then determine the location of each required resource.
Some legacy hardware simply can't 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.
Manual, semi-automated and fully automated P2V
There are three main strategies for P2V migration: manual, semi-automated and fully automated. P2V can be done manually by creating or defining a virtual environment and then reinstalling the OS, applications and data on it. This can be a tedious and uncertain process, especially if the new environment contains substantially different hardware than the old environment.
To streamline the operation, part or all of the migration can partially or automatically be carried out by means of specialized programs known as migration tools. P2V using a migration tool is much faster than manually rebuilding the contents of a physical system in a VM. This is because of the automation involved in migration. For example, a feature in a P2V tool could include automatic discovery, which helps in transitioning from physical to virtual systems with limited or no help from the end user. Any additional customization is then made to the image.
A semi-automated tool assists the user in migrating a physical machine to a VM. For example, VMware vCenter Converter can convert both Windows- and Linux-based physical machines, and support numerous image formats. VMware vCenter Converter features a centralized management console and can convert both local and remote machines. Local installation enables a user to migrate local machines to a VM, while remote installation enables a user to migrate a system remotely via a client system. VMware vCenter Converter can also perform hot and cold migrations. A hot migration occurs when the system being migrated is in a running state, and cold migrations are when the system is offline. Some physical machines, such as Active Directory controllers, aren't recommended to be converted via a hot migration. Cold migrations are recommended for systems such as SQL servers that update regularly. Additionally, vCenter Converter will convert physical machines, Hyper-V VMs and more. However, VMs created by VMware vCenter Converter will only support other VMware software as a destination.
Fully automated P2V tools can migrate a physical machine to a VM without any assistance from the end user. An example of a fully automated P2V tool is PlateSpin Migrate. PlateSpin Migrate can automatically discover Windows and Linux machines, add those machines to workgroups -- only if PlateSpin Migrate is installed on a Windows server and is on the same domain as other Windows servers -- as well as capture and deploy server images. PlateSpin Migrate can also perform multiple scheduled migrations or manual migrations. It can perform P2V as well as other migration types, such as migrating VMs through different virtualization formats or migrating systems and data from VMs to physical machines.
Pros and cons of P2V
P2V methodologies provide consistent ways for migrating physical hardware to VMs; however, someone manually converting a physical machine to a VM or using P2V software should keep these pros and cons in mind.
One advantage of P2V migration is that less hardware, physical space, power consumption and repairs are needed to run a VM; because of this, migrating to VMs saves operating expenses. Also, VMs can run on multiple platforms, expanding migration options. With P2V migrations, old hardware can be phased out and space can be saved because multiple VMs can run on a single server. In addition, if the hardware a VM is on fails, the VM can be placed on a working server with minimal downtime.
P2V doesn't remove any configuration issues with the system or applications when migrated. Also, some legacy hardware can't be emulated in a virtual infrastructure. Finally, specialized hardware, such as USB devices or video cards, might require significant configurations or might not migrate correctly.