Virtualization Glossary of Terms You Should Know
by Bridget.Giacinto, on May 19, 2014 10:01:09 AM
Virtualization brings with it a whole host of new terms. As with any new technology, it’s important to understand all of the new terminology associated with the technology. Although a variety of different technologies fall under the umbrella of virtualization, in general it refers to the ability to run multiple operating systems and applications on the same physical hardware.
Virtualization software, also known as a hypervisor, acts as a layer between the software and the hardware. Hypervisor software essentially emulates the hardware using software. There are two primary hypervisor software solutions, Hyper-V and VMware, although there are other players in the space including Citrix XenServer.
Put simply, when you run a different operating system on top of the primary operating system, this secondary operating system is referred to as a virtual machine. Virtualization allows you to run multiple virtual machines (called Guests) on a single physical machine (called a Host), meaning you can share the same CPU, memory, video card, hard disk etc. By sharing hardware, you save not only on the cost of the hardware, but also on the energy needed to cool that hardware.
One of the benefits of virtualization is that it is highly scalable and efficient. In just minutes, you can spin up a new virtual machine, copy a VM or move it to a new host server as needed to better utilize your hardware.
Virtualization Glossary of Terms You Should Know:
Virtualization – Refers to the technology that allows for the creation of software-based virtual machines that can run multiple operating systems from a single physical machine.
Host Machine –Physical machine that hosts one or more virtual machines.
Virtual Machine (Guest VM) – A self-contained software emulation of a machine, which does not physically exist, but shares resources of an underlying physical machine.
Hypervisor – Software that manages virtual machines, allowing them to interact directly with the underlying hardware.
VM Cluster – A collection of VM Hosts that act as a single large host. If one of the hosts are removed, all of the VMs that the host was running seamlessly continue running on the other hosts. A true VM cluster requires shared storage such as a SAN/NAS device.
P2V (Physical to Virtual) – Refers to the process of migrating operating systems, applications and data from the hard disk of a physical server to a virtual machine.
VM Snapshot – Preserves the state and data of a virtual machine at a given point in time, allowing for recovery at a single point in time for a VM. Snapshots are NOT a way to do backups, but part of the technology used to create snapshots are used by backup software to do backups correctly.
VM Backup – Virtual machine backup can be performed multiple different ways depending on the backup software and the type of hypervisor that the VM guest resides on. The backup software guards against data loss and can be used to recover files in the event of hardware failure or other disaster.
VM Single File Restore – The ability to restore a single file from a virtual machine rather than restoring the entire machine. Without this feature, VM backup software would need to be installed on both the host and the guests in order to retrieve a single file from a virtual machine.
VM Replication – The ability to replicate virtual machines at the server virtualization level using replication software. Provides redundancy for quick VM recovery and reduced downtime in the event of failure or disaster.
Types of Virtualization: (Categorization Layers)
Server Virtualization – Partitioning of a physical server into smaller virtual servers in order to better utilize server resources.
Application Virtualization – The separation of the installation of an application from the underlying operating system on which it is executed. Application virtualization is layered on top of other virtualization technologies, allowing computing resources to be distributed dynamically in real-time.
Network Virtualization – The process of combining hardware and software network resources to create a single pool of resources that make up a virtual network that can be accessed without regard to the physical component.
Storage Virtualization – The process of consolidating the physical storage from multiple network storage devices so that it appears to be a single storage unit.
Desktop Virtualization – The process of virtualizing desktop computers using virtualization software, such that the desktop computer and the associated operating system and applications are separated from the physical client device that is used to access it.
Virtual Desktop Infrastructure (VDI) – The practice of hosting a desktop environment within a virtual machine that runs on a centralized or remote server.
Although this is not a complete virtualization glossary of terms, it should help you to better understand what people are talking about when they refer to going virtual.