Master the CHFI Challenge 2025: Crack the Code and Become a Cyber Sleuth!

The smallest allocation unit of a hard disk is a cluster. A cluster consists of one or more sectors, which are the smallest physical storage units on a hard disk, typically made up of 512 bytes or 4KB. When data is written to the disk, it is allocated in clusters, meaning that even small files consume an entire cluster's worth of space. This is essential for the file system to manage files and directories efficiently on the disk.

While spinning tracks refer to the circular paths on the disk where data is written and read, and disk platters are the physical disks themselves that store data, neither represent the smallest unit of data allocation for file storage. Slack space refers to the unused space in a cluster that arises when a file does not occupy all the space available in that cluster. Although slack space is an important concept in data recovery and forensic analysis, it is not an allocation unit but rather a consequence of how clusters are used for storage. Therefore, the correct answer identifies clusters as the basic unit for allocating space on a hard disk.