A logical disk is a device that provides an area of usable storage capacity on one or more physical disk drive components in a computer system. Other terms that are used to mean the same thing are partition, logical volume, and in some cases a virtual disk (vdisk).
The disk is described as logical because it does not actually exist as a single physical entity in its own right. There are many ways to define a logical disk or volume. Most modern operating systems provide some form of logical volume management which allows the creation and management of logical volumes.
Logical disks are also defined at various levels in the storage infrastructure stack. From top to bottom :
- Operating System : Defines partitions on the disks to which it has visibility (these disks may be logical themselves)
- SAN : If the SAN is virtualized, a device in the same presents logical disks (vdisk) to the host operating systems
- Storage Subsystem : Usually providing some form of RAID where logical disks (partitions) are presented to the SAN from the RAID arrays themselves. The RAID arrays actually contain the physical disks.
Read more about Logical Disk: Why Do We Need Them?
Famous quotes containing the words logical and/or disk:
“The novel is not “a crazy quilt of bits”; it is a logical sequence of psychological events: the movements of stars may seem crazy to the simpleton, but wise men know the comets come back.”
—Vladimir Nabokov (1899–1977)
“Unloved, that beech will gather brown,
This maple burn itself away;
Unloved, the sun-flower, shining fair,
Ray round with flames her disk of seed,
And many a rose-carnation feed
With summer spice the humming air;”
—Alfred Tennyson (1809–1892)