What are the features of ZFS?

The Z file system is a free and open source logical volume administrator worked by Sun Microsystems which is now possessed by Oracle, for use in their Solaris operating system. It is a progressive file system that in a general sense changes the way file systems are controlled, with highlights and advantages not found in some other file system accessible today. ZFS gives an enormously simplified administration model. Though the use of a hierarchical file system layout, property inheritance, and automatic management of mount points and NFS share semantics, ZFS make it simple to make and oversee file system without requiring numerous commands or altering configuration files(/etc/fstab).

ZFS is used for managing multiple disks and their raid setups. Features of ZFS include:

• Pooled storage
• Snapshots
• Copy-on-write
• RAID-Z
• Data integrity verification and automatic repair
• Maximum 16 Exabyte file size
• Maximum 256 Quadrillion Zettabytes storage

ZFS is robust, scalable, fast, shielded, and easy to administer. It is licensed under the CDDL and incompatible with GPL, not possible for ZFS to be distributed along with
the Linux Kernel. However, we can install using the third party, as is the case with zfsonlinux.org

Let’s break down a couple of those features.

1. Pooled Storage

The storage is managed in ZFS using the concept of Storage Pools. ZFS wiped out volume management which was introduced in the older file systems to provide a  representation of a single device so that file systems would not need to be modified for the multiple devices because file system had no control over the physical placement of data on the virtualized volumes. ZFS assembled devices into storage pools instead of creating virtualized volumes. The storage pool typifies the physical qualities of the storage and goes about as an arbitrary data store from which file systems can be made. In ZFS, file systems are spread over into drives on the pool, allowing them to share disk space with file systems. Also, if the new storage is added to the pool, all file systems in the pool immediately use the storage without any supplementary work.

2. Snapshots

ZFS Snapshot is a read-only copy of zfs file system used to track changes in the file system and is one of the most powerful features of ZFS. Snapshots are made by utilizing the `zfs snapshot` or `zfs snap` command. The snapshot contains a read-only, point-in-time copy of a file system and will not consume any extra space in the ZFS pool until the block references are changed.  Snapshots can be utilized to store a state of a file system at a specific point and can be moved back to the very same state. Also, we can extract some files from the snapshot without any complete rollback. All modifications made since the snapshot will be lost.

3. Copy-on-write

Copy-on-write is the next pleasing feature of ZFS. On most files system, when data is overwritten, it vanishes forever. Unlike other file systems, Copy-on-write (COW) is a data storage technique in which creating a copy of the data block that is going to be modified, rather than modify the data block directly.  Also, need to update the pointers to new block location. This ensures that if the system crashes, the old data will be preserved. Also, we can avoid fsck as normally we do after the system crash.