76 lines
3.5 KiB
Markdown
76 lines
3.5 KiB
Markdown
---
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navigation: true
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title: ZFS
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main:
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fluid: false
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---
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:ellipsis{left=0px width=40rem top=10rem blur=140px}
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# ZFS
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::alert{type="info"}
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🎯 __Objectives:__
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- Understand what ZFS is and why it's useful
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::
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ZFS is widely used in the world of servers, NAS systems (like FreeNAS / TrueNAS), virtualization, and even by tech-savvy individuals who want reliable storage. It is both a _file system_ (like NTFS for Windows, EXT4, FAT32, etc.) and a _volume manager_ (similar to LVM).
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To put it simply:
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- A **volume manager** organizes physical storage (like one or more hard drives).
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- A **file system** organizes how data blocks are written, read, and deleted within those volumes.
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ZFS goes far beyond traditional file systems in terms of performance and features.
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Here’s what we’re most interested in:
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- Its __snapshot management__ features, allowing you to quickly roll back in case of issues.
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- Its support for disk groupings and [__RAID-like structures__](/general/storage/raid) (Z-Mirror, RAIDZ1, RAIDZ2, RAIDZ3).
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- Its __automatic recovery of corrupted data__ (through scrubbing).
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- Its performance, enhanced by RAM caching (ZFS ARC).
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- Its robust error notifications and monitoring.
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## Structure
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---
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ZFS has a unique structure:
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- **vdev** (virtual device): a group of physical or virtual disks.
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- **zpool**: a collection of vdevs configured as a single storage pool. A zpool can contain multiple vdevs, but a vdev belongs to only one zpool.
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- **dataset**: a logical data container within a zpool. Each dataset can have its own settings (compression, quotas, permissions, etc.).
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There are several dataset types:
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- **file system**: a standard ZFS filesystem, mounted without storage quotas.
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- **zvol**: a "virtual disk" with a defined size, which you can format and partition as if it were a physical disk.
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- **snapshot**: a frozen-in-time version of another dataset. Snapshots can be created manually or through backup tools. They can be mounted to browse data as it was at the snapshot time.
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## Why ZFS over others?
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---
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### Data Integrity
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ZFS continuously checks that your stored data hasn't become corrupted. Every block of data is associated with a checksum, allowing ZFS to detect even the smallest alteration. If corruption is found and a healthy copy exists elsewhere, ZFS can repair the data automatically.
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### Built-in RAID
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ZFS includes its own volume management system (vdevs). You can build a zpool using multiple disks—similar to traditional [RAID](/general/storage/raid) setups—but with more flexibility. For example:
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- **Z-mirror** → equivalent to RAID 1
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- **RAIDZ1** → equivalent to RAID 5 (tolerates 1 disk failure)
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- **RAIDZ2** → equivalent to RAID 6 (tolerates 2 disk failures)
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- **RAIDZ3** → tolerates up to 3 disk failures
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ZFS handles all this natively—no external RAID software needed.
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::alert{type="info"}
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:::list{type="info"}
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- Check out the [article on RAID](/general/storage/raid) to find the right solution for your needs.
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:::
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::
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### Snapshots and Clones
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ZFS allows you to create snapshots—instantaneous images of a dataset's state. Snapshots take up minimal space and can be scheduled frequently. You can also create clones: writable copies of snapshots.
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### Compression and Deduplication
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ZFS can compress data on the fly (transparently to the user), saving disk space. It also supports deduplication (removing duplicate data), though this feature requires a lot of memory and is not recommended for all use cases.
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---
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Now you know why ZFS is *the* file system to deploy on your NAS. |