What's the definition of, and distinction between, a volume and a partition?
Wikipedia notes that a partition is created before any files or directories are written to disk. But, then, in the next breath, continues that: "Each partition, or volume..."
While I realize that the complexity increases quickly, what is best way to distinguish between these concepts?
Partitions
Storage media (DVD's, USB sticks, HDD's, SSD's) can all be divided into partitions, these partitions are identified by a partition table.
The partition table is where the partition information is stored, the information stored within here is basically where the partition starts and where it finishes on the disc platter.
Volumes
A Volume is a logical abstraction from physical storage. Large disks can be partitioned into multiple logical volumes Volumes are divided up into fixed size blocks or a cluster or blocks.
We don't see the partition as this is sorted by the file system controller but we see volumes as they are logical and are provided by a gui with a hierarchical structure and human interface. When we request to see a file it runs through a specific order to view that information from within the volume on the partition:
- Application created the file I/O request
- The file system creates a block I/O request
- Block I/O drive accesses the disk
Source What is the difference between Volume and Partition?, answer by Daniel Everitt
Additional notes
A Partition is limited to a single disk.
A Disk may contain one or multiple partitions.
A Volume may span multiple disks as there are several types of Volume:
Creating a Volume or Partition
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.
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Depending on the number of available unallocated volumes, you see one or more options for the type of volume, including the following:
- New Simple Volume
- New Spanned Volume
- New Striped Volume
- New Mirrored Volume
- New RAID-5 Volume
Of the above only a Simple Volume resides on a single disk. The others reside (in parts) on multiple disks (read on for more information on volume types).
Source Partitions and Volumes
Types of Volumes for Dynamic Disks
When you are working with a volume on a Dynamic Disk, you can choose to extend or span that volume across multiple drives, you can stripe or mirror, or in server editions you can even use RAID 5. There’s also not a real limit on the number of volumes you can have, although it wouldn’t make sense to have a huge number of them.
Here are the types of volumes you can create on a Dynamic Disk:
- Simple Volume – this is a regular “partition”. If the disk type is “Basic”, this creates an actual partition.
- Striped Volume – data is striped across multiple hard drives so that every other segment of data is staggered between the drives for maximum performance. There is no redundancy.
- Spanned Volume – data fills up on one drive and then fills up the next drive as it gets more full. Two or more drives are basically taped together to make a bigger disk. There is no redundancy here either.
- Mirrored Volume – for home users, this is the only form of redundancy that you will get with software options. Read performance should be faster, but write performance will possibly be slightly slower, since Windows has to write to both drives for everything.
- RAID5 Volume – only works on server editions, but it can stripe across 3 or more hard drives and include a parity stripe to prevent data loss if a drive was to fail.
Note: you can’t use a Dynamic Disk for a removable / portable drive.
Source Windows Admin: Understanding Hard Drive Partitioning with Disk Management
They are used interchangeably but in a strict sense that is probably wrong. A Partition can only be a logical space defined within a larger physical space.
A Volume on the other hand can be a descriptor for both a Physical Space, example Macintosh HD, or Logical space within a Drive such as a Windows 10 partition within the Macintosh HD. When Windows is booting up in this case, it is loading the Windows 10 Volume, which again is really a partition.
