Btrfs: Difference between revisions
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{{note| Use [https://github.com/nix-community/disko/ disko] to manage your NixOS storage layout declaratively. The following shows a manual approach as seen in traditional Linux distributions.}} | {{note| Use [https://github.com/nix-community/disko/ disko] to manage your NixOS storage layout declaratively. The following shows a manual approach as seen in traditional Linux distributions.}} | ||
= Installation = | = Installation of NixOS on btrfs = | ||
{{note|The following example is for EFI enabled systems. Adjust commands accordingly for a BIOS installation.}} | {{note|The following example is for EFI enabled systems. Adjust commands accordingly for a BIOS installation.}} | ||
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== Deduplication == | == Deduplication == | ||
Files with (partially) equal contents can be deduplicated using [https://github.com/Zygo/bees bees] or [https://github.com/markfasheh/duperemove duperemove]. The [https://btrfs.readthedocs.io/en/latest/Deduplication.html upstream wiki entry] on deduplication provides an overview of available features of these programs. | |||
Files with (partially) equal contents can be deduplicated using [https://github.com/Zygo/bees bees] or [https://github.com/markfasheh/duperemove duperemove]. | |||
bees can be configured in <code>configuration.nix</code>: | bees can be configured in <code>configuration.nix</code>: | ||
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== Subvolumes == | == Subvolumes == | ||
To display all subvolumes within a mounted btrfs filesystem: | |||
<syntaxhighlight lang="bash"> | |||
btrfs subvolume list -t /mnt | |||
</syntaxhighlight> | |||
To create a new subvolume at a specified location: | |||
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash"> | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
To remove an existing subvolume: | |||
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash"> | ||
btrfs subvolume delete /mnt/nixos | btrfs subvolume delete /mnt/nixos | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Top-level vs nested subvolumes === | |||
In btrfs, subvolumes can be created either at the top level of the filesystem or within other subvolumes. | |||
* Top-level subvolumes are created directly under the filesystem's root. By default, the root volume ID is 5. Top-level subvolumes are easier to snapshot, roll back or destroy independently. This is good for things such as <code>/home</code> or <code>/nix</code>. | |||
* Nested subvolumes are created inside an existing subvolume or directory within the filesystem. All nested subvolumes inherit the mount status of their parent unless mounted separately. This layout is useful for organizing related subvolumes under a common namespace. For example, a top-level subvolume such as <code>/srv/nfs</code> can contain multiple nested subvolumes like <code>/srv/nfs/export1</code> and <code>/srv/nfs/export2</code>. | |||
== Snapshots == | == Snapshots == | ||
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= Tips and tricks = | = Tips and tricks = | ||
== Backup == | |||
[[Btrbk]] is a tool for creating snapshots and remote backups of btrfs subvolumes. | |||
== Installation with encryption == | == Installation with encryption == | ||
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== Convert Ext3/Ext4 system partition to Btrfs == | == Convert Ext3/Ext4 system partition to Btrfs == | ||
{{Warning|Note that migrating your existing root filesystem can cause data loss or make your system unbootable. Make sure to backup the partition or your files. Proceed only if you know what you're doing!}} | |||
To convert the existing filesystem (Ext3/4) to Btrfs, boot into a NixOS live system and run the following commandː<syntaxhighlight lang="sh"> | To convert the existing filesystem (Ext3/4) to Btrfs, boot into a NixOS live system and run the following commandː<syntaxhighlight lang="sh"> | ||
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btrfs subvolume delete /btrfs/ext2_saved | btrfs subvolume delete /btrfs/ext2_saved | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== TRIM support === | |||
{{main|Filesystems#SSD TRIM support}} | |||
Refer to [https://btrfs.readthedocs.io/en/latest/Trim.html btrfs docs] on how Trim works with btrfs through the <code>discard</code> mount option. | |||
[[Category: Configuration]] | [[Category: Configuration]] | ||
[[Category:Filesystem]] | [[Category:Filesystem]] | ||