An Exascale block volume is an arbitrary-sized allocation of storage space, which can be used as an Exascale Direct Volume (EDV) attachment or iSCSI target.

Internally, each volume is an Exascale file with special properties that identify it as block storage space. Like other Exascale files, physical space for the volume is only materialized when data is written to the volume.

Each volume is created in a user-specified vault. You can also optionally specify the physical media type used to store the volume. By default, volumes are stored on hard disk drives (HC media type).

Each volume can be associated with a series of optional attributes, which define the detailed characteristics of the volume. For example, the redundancyType attribute specifies the number of data copies (mirrors) that are maintained. Attributes like maxReadIops and maxWriteIops constrain the system resources that a volume is allowed to consume.

To use a volume, you must create a volume attachment. Depending on the type of attachment that you create, the volume is marked for use as an EDV attachment or iSCSI target.

Unlike regular Exascale files, volumes are not subject to access controls defined by user privileges and ACLs. Consequently, volume administration tasks (attachment, detachment, modification, and so on) must be performed by the volume owners or an Exascale cluster administrator (having the cl_admin privilege).