LVM: Difference between revisions

Line 1:

[https://en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux) ~~The~~ Logical Volume Manager] (LVM) provides means to dynamically organize partitions.

Linux's '''[https://en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux) Logical Volume Manager] (LVM)''' provides means to dynamically organize partitions. For example, partitions can be created, moved, resized and deleted regardless of fragmentation on disk.

== Basic Setup ==

~~LVM manages three types:~~

~~; Physical volume (PV)~~ : ~~Space reservation consisting of a disk partition, a whole disk, a meta device, or a loopback file.~~

LVM manages four basic building blocks:

~~; Volume group (VG) : Group of physical volumes.~~

~~; Logical volume (LV) : Space reservation inside a volume group, which may be laid across multiple physical volumes.~~

=== Create ~~a logical volume~~ ===

; Physical volume (PV) : Unix block device node reserved for use by LVM. Examples: a disk partition, a whole disk (i.e. without a partition table), a meta device, or a loopback file.

; Volume group (VG) : Group of PVs for allocating PEs to LVs.

; Logical volume (LV) : "Virtual partition" composed of PEs inside a VG.

; Physical extent (PE) : The smallest contiguous [[wikipedia:Extent (file systems)|extent]] (default 4 MiB) in the physical volume that can be allocated to an LV.

=== Create an LV ===

Line 21:

Line 23:

</syntaxHighlight>

=== Use the ~~Logical Volume~~ ===

=== Use the LV ===

in your <code>configuration.nix</code>:

Line 32:

Line 34:

== Booting with special LVM Modes ==

LVM provides a number of special features such as creating snapshots, ~~raid~~ for single ~~Logical Volumes~~ and much more. If you want to use these devices on bootup, the associated <code>dm-*</code> kernel module must be provided in the initrd (see for example {{Issue|33646}}) . This is a non-exhaustive list of features and the corresponding kernel module and other options to put into your <code>configuration.nix</code>:

LVM provides a number of special features such as creating snapshots, RAID for single LVs and much more. If you want to use these devices on bootup, the associated <code>dm-*</code> kernel module must be provided in the initrd (see for example {{Issue|33646}}). This is a non-exhaustive list of features and the corresponding kernel module and other options to put into your <code>configuration.nix</code>:

boot.initrd.kernelModules = [

Line 47:

Line 49:

=== NixOps ===

NixOps can repartition Hetzner Physical Machines, see [[https://nixos.org/nixops/manual/#idm140737318354032 NixOps Manual]].

NixOps can repartition Hetzner Physical Machines, see [https://nixos.org/nixops/manual/#idm140737318354032 NixOps Manual].

=== Disko ===

[[Disko]] provides means to automatically generate the creation and configuration of logical volumes, see https://github.com/nix-community/disko

== See also ==

* [https://wiki.archlinux.org/title/LVM The corresponding ArchWiki page]

[[Category:Filesystem]]

@@ Line 1: / Line 1: @@
-[https://en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux) The Logical Volume Manager] (LVM) provides means to dynamically organize partitions.
+Linux's '''[https://en.wikipedia.org/wiki/Logical_Volume_Manager_(Linux) Logical Volume Manager] (LVM)''' provides means to dynamically organize partitions. For example, partitions can be created, moved, resized and deleted regardless of fragmentation on disk.
 == Basic Setup ==
-LVM manages three types:
-; Physical volume (PV) : Space reservation consisting of a disk partition, a whole disk, a meta device, or a loopback file.
+LVM manages four basic building blocks:
-; Volume group (VG) : Group of physical volumes.
-; Logical volume (LV) : Space reservation inside a volume group, which may be laid across multiple physical volumes.
-=== Create a logical volume ===
+; Physical volume (PV) : Unix block device node reserved for use by LVM. Examples: a disk partition, a whole disk (i.e. without a partition table), a meta device, or a loopback file.
+; Volume group (VG) : Group of PVs for allocating PEs to LVs.
+; Logical volume (LV) : "Virtual partition" composed of PEs inside a VG.
+; Physical extent (PE) : The smallest contiguous [[wikipedia:Extent (file systems)|extent]] (default 4 MiB) in the physical volume that can be allocated to an LV.
+=== Create an LV ===
 <syntaxHighlight lang=bash>
@@ Line 21: / Line 23: @@
 </syntaxHighlight>
-=== Use the Logical Volume ===
+=== Use the LV ===
 in your <code>configuration.nix</code>:
@@ Line 32: / Line 34: @@
 == Booting with special LVM Modes ==
-LVM provides a number of special features such as creating snapshots, raid for single Logical Volumes and much more. If you want to use these devices on bootup, the associated <code>dm-*</code>  kernel module must be provided in the initrd (see for example {{Issue|33646}}) . This is a non-exhaustive list of features and the corresponding kernel module and other options to put into your <code>configuration.nix</code>:
+LVM provides a number of special features such as creating snapshots, RAID for single LVs and much more. If you want to use these devices on bootup, the associated <code>dm-*</code> kernel module must be provided in the initrd (see for example {{Issue|33646}}). This is a non-exhaustive list of features and the corresponding kernel module and other options to put into your <code>configuration.nix</code>:
 <syntaxHighlight lang=nix>
 boot.initrd.kernelModules = [
@@ Line 47: / Line 49: @@
 === NixOps ===
-NixOps can repartition Hetzner Physical Machines, see [[https://nixos.org/nixops/manual/#idm140737318354032 NixOps Manual]].
+NixOps can repartition Hetzner Physical Machines, see [https://nixos.org/nixops/manual/#idm140737318354032 NixOps Manual].
 === Disko ===
 [[Disko]] provides means to automatically generate the creation and configuration of logical volumes, see https://github.com/nix-community/disko
+== See also ==
+* [https://wiki.archlinux.org/title/LVM The corresponding ArchWiki page]
 [[Category:Filesystem]]