About

Every file system implements the notion of block (unit of persistent storage) where a file is split into one or more blocks.

The block size is the smallest unit of data that a file system can store.

If you store a file that's 1k or 4b with a block size of 4kb, it'll take up one block.

There is one request per block

OS File System

The block of a operating system file system is known as a cluster.

Windows File Properties Size On Disk