What are the four main levels of virtualization?

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Virtualization levels refer to the different levels at which virtualization can be applied, when dealing with data storage virtualization solutions. These levels differ and can involve virtualization at the hard drive level all the way up to a full virtualized solution at the file system level.

There are four main levels which are described below.

Server Level

This level is fairly self explanatory. It involves the management of physical hard drives, within a server's operating system environment. For example it could involve logically partitioning a server's hard drive.

Storage Device Level

This is virtualization at the storage volume level and can involve techniques such as data striping or data mirroring. The most well-known storage device level virtualization technology is RAID. RAID 0 uses striping, which is a technique where data is written across multiple storage devices. However an end-user can access this data although it is stored on single local storage volume.

Other forms of RAID (such as RAID 1) use mirroring techniques where data is written on to two separate hard drives at the same time. Some forms of raid even use a combination of both striping and mirroring, making them an even more effective storage device level virtualization technology and backup solution.

Fabric Level

This level of virtualization involves allowing storage devices to be independent of physical hardware or servers. This means that massive pools of storage areas can be created, while logically appearing as a single storage solution. Usually a management interface is required to manage storage systems at this level, because they are independent from server management. A storage area network (SAN) volume controller will carry out virtualization at this level.

File System level

This level provides users with the most benefits because storage is completely virtualized. Data can be shared, protected or allocated from within software at this level, rather than at the physical hard drive level, which requires much more effort and resources. By using file system level virtualization the size of virtualized data pools can be manipulated at will, while complete clusters of data can be moved from one location to another, in the form of virtual hard drives, with complete ease.

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