A block storage can be usable if it is attached to a compute system without an operating system

Explanation

The basic block storage architecture consists of three components: the block storage, the compute system, and the operating system running on the compute system. The block storage is either physically or logically attached to the compute system. The operating system, which runs on the the compute system, then recognizes the block storage as available. The operating system formats or makes the block storage ready for use.