A periodic snapshot task allows scheduling the creation of read-only versions of pools and datasets at a given point in time.
How should I use snapshots? Snapshots do not make copies of the data, so creating one is quick. It is common to take frequent snapshots every 15 minutes, even for large and active pools. A snapshot with no file changes takes no storage space, but as file changes happen, the snapshot size changes to reflect the size of the changes.
ZFS supports deduplication as a feature. Deduplication means that identical data is only stored once, and this can greatly reduce storage size. However deduplication is a compromise and balance between many factors, including cost, speed, and resource needs. It must be considered exceedingly carefully and the implications understood, before being used in a pool.
Deduplication on ZFS Deduplication is one technique ZFS can use to store file and other data in a pool.
Resilvering is a process that copies data to a replacement disk. Complete it as quickly as possible. Resilvering is a high priority task. It can run in the background while performing other system functions, however, this can put a higher demand on system resources. Increasing the priority of resilvers helps them finish faster as the system runs tasks with higher priority ranking.
Use the Resilver Priority screen to schedule a time where a resilver task can become a higher priority for the system and when the additional I/O or CPU use does not affect normal usage.
Zettabyte File system (ZFS) is an advanced, modern file system specifically designed to provide features not available in traditional UNIX file systems. Sun originally developed and intended ZFS to be an open-source file system that can be ported to other operating systems. After the Oracle acquisition of Sun, some of the original ZFS engineers founded OpenZFS to provide continued, collaborative development of the open source version.
ZFS Feature Overview Here is an overview of the features provided by ZFS.
Introduced in OpenZFS version 2.1.0 and initially supported in TrueNAS SCALE 23.10 (Cobia), declustered RAID (dRAID) is an alternate method for creating OpenZFS data virtual devices (vdevs).
Intended for storage arrays with numerous attached disks (>100), the primary benefit of a dRAID vdev layout is to reduce resilver times. It does this by building the dRAID vdev from multiple internal raid groups that have their own data and parity devices, using precomputed permutation maps for the rebuild IO, and using a fixed stripe width that fills storage capacity with zeroes when necessary.
The ZIL and SLOG are two frequently misunderstood concepts in ZFS.
ZFS is taking extensive measures to safeguard your data and it should be no surprise that these two terms represent key data safeguards. What is not obvious, however, is that they only come into play under very specific circumstances.
The first thing to understand is that ZFS behaves like any other file system with regard to asynchronous and synchronous writes.
Visualize and compare different RAID layouts and settings including stripe, mirror, RAIDZ1, RAIDZ2, RAIDZ3, and dRAID.
ZFS Capacity Graph originally created by Jason Rose.
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