logical volume management (LVM)

Logical volume management (LVM) is a form of storage virtualization that offers system administrators a more flexible approach to managing disk storage space than traditional partitioning. This type of virtualization tool is located within the device-driver stack on the operating system. It works by chunking the physical volumes (PVs) into physical extents (PEs). The PEs are mapped onto logical extents (LEs) which are then pooled into volume groups (VGs). These groups are linked together into logical volumes (LVs) that act as virtual disk partitions and that can be managed as such by using LVM.

The goal of LVM is to facilitate managing the sometimes conflicting storage needs of multiple end users. Using the volume management approach, the administrator is not required to allocate all disk storage space at initial setup. Some can be held in reserve for later allocation. The sysadmin can use LVM to segment logically sequential data or combine partitions, increasing throughput and making it simpler to resize and move storage volumes as needed. Storage volumes may be defined for various user groups within the enterprise, and new storage can be added to a particular group when desired without requiring user files to be redistributed to make the most efficient use of space. When old drives are retired, the data they contain can be transitioned to new drives -- ideally without disrupting availability of service for end users.