volsize

Volsize is a term used in computing to denote the size or capacity of a volume or virtual block device. It is commonly encountered as a property name in storage management systems to express the allocated storage for a given volume. The exact meaning and how it is managed depend on the specific system or tool in use.

In ZFS, volsize is a property of a zvol, which is a ZFS volume that presents as a block device. A zvol can be used as a virtual disk for virtual machines or other software. The volsize property defines the size of the zvol in bytes and can be viewed with a command such as zfs get volsize pool/vol. Volumes are typically created with a size parameter, for example via zfs create -V 100G pool/vol. The volsize can be adjusted later by setting a new size with zfs set volsize=newsize pool/vol. Increases are common and straightforward; decreases require caution and are sometimes constrained by existing data and snapshots.

Outside of ZFS, volsize may appear as a general parameter in other storage or virtualization tooling to indicate the total capacity of a volume. In these contexts, volsize serves the same basic purpose: to specify how much storage space is allocated for the volume, using units such as bytes, kilobytes, megabytes, or larger (e.g., G, T).

Notes and considerations:

- Volsize represents allocated capacity, not necessarily the usable filesystem capacity inside the volume.

- Unit specification is important to avoid misconfiguration (bytes vs. powers of two).

- Resizing a volume (especially shrinking) can have data safety implications and may require appropriate precautions or downtime.

See also: volume size, ZFS, zvol.