Differences between volume, partition and drive

1. A drive is a physical block disk. For example: /dev/sda.

2. A partition A drive can be divided into some logic block disk. These logic block disk are named partition. For example: /dev/sda1, /dev/sda2.

3. A volume is also a logic block disk. Volume is a concept involved with partition. A volume can contain many partition. You can take a look at LVM project to understand the concept of a volume. http://sourceware.org/lvm2/.

The term drive refers to a physical storage device such as a hard disk, solid-state disk, removable USB flash drive etc. In Unix-like operating systems devices are represented by special file system objects called device nodes which are visible under the /dev directory.

Storage devices are labeled under /dev according to the type of device followed by a letter signifying the order in which they were detected by the system. In Linux prior to kernel version 2.6.20 the prefix hd signified an IDE device, so for instance the device files /dev/hda, /dev/hdband /dev/hdc corresponded to the first, second and third IDE device respectively. The prefix sdwas originally used for SCSI devices, but is now used for all PATA and SATA devices, including devices on a IDE bus. If there are more than 26 such devices in the system, devices from the 27th onwards are labeled /dev/sdAa, /dev/sdAb and so on.

A physical storage device can be divided into multiple logical storage units known as partitions. Each partition will show up under /dev as a separate device node. A number after the device letter signifies the number of the partion, so for example the device node files /dev/sda1 and /dev/sda2refer to the first and second partition of the first PATA device. Note that on PCs using MBR partitioning, due to the limit of four primary paritions and the way extended partitions are handled the partition numbering can slightly differ from the actual partition count.

Other Unix-like systems may refer to disks and partitions in other ways. For example, FreeBSD uses /dev/adaX (where X is one or more digits) to refer to PATA disks and /dev/adaXpY (where X and Y are both one or more digits) to refer to partitions on PATA disks.

The term volume in Linux is related to the Logical Volume Manager (LVM), which can be used to manage mass storage devices. A physical volume is a storage device or partition. A logical volumecreated by the LVM is a logical storage device which can span multiple physical volumes.

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

A partition is a just a space crafted out of a disk.
For example- you could set aside a space of 100 GB for a partition from a hard disk of 1 TB.

A volume is a partition that has been formatted into a filesystem.
A partition is of little use unless formatted. And when we format a partition into NTFS, FAT32, ext4 etc, it becomes a volume and is usable.

You can create a new volume or partition on any disk that has empty space. If the disk is dynamic, a volume is created. If the disk is a basic disk, a primary partition is created. If the empty space is part of an extended partition, a new logical drive will be created. All of them called a simple volume, but each one a different structure.

Note You can no longer create an extended partition in Disk Manager. If you need to create an extended partition, you need to use DiskPart.exe. But there's really no longer any need for extended partitions.

Each partition will show up under /dev as a separate device node. A number after the device letter signifies the number of the partion, so for example the device node files /dev/sda1 and /dev/sda2 refer to the first and second partition of the first PATA device. Note that on PCs using MBR partitioning, due to the limit of four primary paritionsand the way extended partitions are handled the partition numbering can slightly differ from the actual partition count.

In Windows Server 2008 the distinction between volumes and partitions is somewhat murky. When using Disk Management, a regular partition on a basic disk is called a simple volume, even though technically a simple volume requires that the disk be a dynamic disk.