ZFS is unusual because, unlike most other storage systems, it unifies both of these roles and acts as both the volume manager and the file system. Therefore, it has complete knowledge of both the physical disks and volumes (including their condition and status, their logical arrangement into volumes), and also of all the files stored on them. ZFS is designed to ensure (subject to suitable hardware) that data stored on disks cannot be lost due to physical errors or misprocessing by the hardware or operating system, or bit rot events and data corruption which may happen over time, and its complete control of the storage system is used to ensure that every step, whether related to file management or disk management, is verified, confirmed, corrected if needed, and optimized, in a way that storage controller cards and separate volume and file managers cannot achieve.
