If the system is not suitable for ZFS, then ZFS may underperform significantly.
ZFS developers Calomel stated in their 2017 ZFS benchmarks that:"On mailing lists and forums there are posts which state ZFS is slow and unresponsive.
ZFS also includes a mechanism for snapshots and replication, including snapshot cloning; the former is described by the Free BSD documentation as one of its "most powerful features", having features that "even other file systems with snapshot functionality lack".
Very large numbers of snapshots can be taken, without degrading performance, allowing snapshots to be used prior to risky system operations and software changes, or an entire production ("live") file system to be fully snapshotted several times an hour, in order to mitigate data loss due to user error or malicious activity.
The ZFS name is registered as a trademark of Oracle Corporation; In 2005, the bulk of Solaris, including ZFS, was licensed as open-source software under the Common Development and Distribution License (CDDL), as the Open Solaris project.
ZFS became a standard feature of Solaris 10 in June 2006.
The vdev is a fundamental part of ZFS, and the main method by which ZFS ensures redundancy against physical device failure.
A device in any vdev can be marked for removal, and ZFS will de-allocate data from it to allow it to be removed or replaced.
Of note, the devices in a vdev do not have to be the same size, but ZFS may not use the full capacity of all disks in a vdev, if some are larger than other. As vdevs are independent, ZFS does not care if different vdevs have different sizes or are built from different devices.
Therefore, it has complete knowledge of both the physical disks and volumes (including their condition, 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 error 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.