Whether you use Windows, macOS, or Linux, you’ve probably heard the terms drive, disk, partition, volume, volume drives, and image being used interchangeably. While that doesn’t hurt from a functional perspective, knowing the differences between these terms is important.
Tip: formatting a hard drive or USB drive? Find out which allocation unit size is best for your drive.
Disk vs. Drive
The terms disk and drive can be some of the most confusing ones for an average user. This is in part due to computer storage terms still suffering from historical hangover.
A disk refers to a physical magnetic platter, like the one found in conventional hard disk drives. It’s the actual physical material that stores all of your data.
A drive is a set of mechanical parts used to read or write data from and to the disk. Traditionally, disks had to be inserted in drives located on the computer. For instance, floppy disks require floppy disk drives to be accessed. Even older hard disks and hard drives were separated physically, unlike today.
With time, disks and drives became small enough to be integrated into a single unit, thus resulting in the hard disk drives (HDDs) that most of us are familiar with.
Today’s best Solid State Drives (SSDs) do not have any physical drive at all but are still called drives, as the term managed to stick. Even the best external hard drives should technically be called external hard disks, as that more accurately defines the device’s functionality.
Good to know: interested in hybrid drives? Check out SSD vs. SSHD and whether hybrid drives are worth it.
Partition vs. Volume
While disks and drives are physical entities (in the strictest sense), partitions and volumes are logical locations on a disk. There are some peculiarities, especially in Windows, as discussed below.
A partition is a portion of a disk with a specific size. It’s literally just a “partition” of your available storage space. Although a partition can be detected by Windows, it doesn’t mean it can be accessed by you yet. A partition doesn’t necessarily have a file system or need to be formatted. That comes next.
A volume is a partition that has been formatted and has a file system and a “drive” letter. It’s the logical part of the disk that you can see and access within your file explorer. Whenever you connect an HDD, SSD, external drive, or flash drive, and it appears in your file browser, you’re seeing the volume. Volumes are sometimes referred to as volume drives or disk volumes, although this is rare.
Windows assigns drive letters to volumes, such as the “C” or “D” drive when you format them to FAT32, exFAT, or NTFS. This further complicates matters, as there’s nothing physical going on here. Technically, Windows should refer to these as volumes and not drives. But, like before, the terminology has stuck.
Your disk can have multiple partitions and volumes, and you can resize them using disk partition management tools or Disk Management in Windows.
Tip: need to format your drive? Learn how to reformat an external hard drive without losing your data.
Virtual Disk vs. Virtual Partition
If you’ve used virtual machines to install Windows in Linux, you may be familiar with the term “virtual disk.”
A virtual disk is the storage space used by a virtual machine. Unlike a physical disk, a virtual disk is just a file on your computer that is used to store all the information required to run a particular virtual machine. The virtual machine accesses and uses this virtual disk just as a physical computer would use a physical disk.
A virtual partition is a combination of two or more partitions that a computer can access, similar to a single partition. Virtual partitions aren’t physically related on a disk; they’re simply related logically and made to appear like an actual partition. Linux often uses partitions from one or even more disks to create virtual partitions.
Tip: working with both VMware and VirtualBox? This guide shows how to convert virtual machines from VMware to VirtualBox and vice versa.
Image
Images are identical snapshots of volumes, but they have no physical hardware related to them. They are copies of one or more volumes, containing every single bit stored on the captured volumes.
You can create an image of any volume, and store it on any other storage device with sufficient free space. Windows makes use of images for system backups (called System Images) that can be used to restore your computer to an earlier working state in case of an OS failure.
An image must be mounted or attached before it can be accessed, just like a volume. You’ll need to use specific tools to read the contents of an image.
Container
Some filesystems also make use of containers. macOS introduced containers with its new file system, Apple File System (APFS), in 2017, replacing the HFS Plus file system.
A container is a logical portion of a disk that stores volumes and other metadata. You can consider APFS containers as Windows partitions, but they function a little differently from the other items on this list.
Within APFS, disks hold containers and containers hold volumes. The volumes within a given container are allowed to share the space allocated to the container, which has a set maximum size. This means the volumes can be flexible, expanding to fit files or shrinking to allow other volumes to grow.
Disks and drives are physical storage spaces that are now often combined into single entities, like HDDs, whereas partitions and volumes are logical separations of a disk that can store data and be accessed by the user. Containers are used in place of partition tables in the APFS filesystem, and images are snapshots of all the data on one or more volumes. You can check your hard disk health in Windows if you’re facing errors or suspect issues with certain volumes.
Image credit: Unsplash. All screenshots by Tanveer Singh.
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