The virtual machine (VM), which is a computer program requires storage for its data. To improve the overall performance of the VM administrator can use virtual storage to display one physical or network-based storage device as various types of storage. The VM can access it without needing to know the underlying hardware.
managing virtual storage requires the careful balance of capacity, performance and cost. Admins must decide whether to use all solid-state drives or hard-drive disks; the kind of storage controllers they should use and how to combine them in a hybrid configuration. IT managers can lower storage costs by using compression and deduplication.
There are three types of virtual storage: physical disks RAID groups, and logical volumes (LV). Physical disks and RAID groups divide physical capacity into smaller units, which applications or servers perceive to be a single storage device. A virtualization layer transforms I/O requests made by the server to the right physical disk.
The virtual storage model minimizes the hardware-related overhead by segregating operating systems from physical devices, and also by providing one point of administration. It also facilitates scalability by automatically altering the physical capacity to meet demand. In addition, it permits administrators to handle a variety of tasks in a non-disruptive fashion such as moving data off storage devices that are being over-utilized. Data migration is a technique that allows this to be accomplished. The granularity of mapping determines the speed at which meta-data updates can be made, how much space is required during migration and how quickly the previous location will become free.