Editing Logical Volume Manager (Linux)

[[wikipedia:Logical_Volume_Manager_(Linux)|LVM]]<ref>http://man7.org/linux/man-pages/man8/lvm.8.html</ref> available in Linux allows manage multiple physical volumes or entire hard disks. It supports among other functionalities:
* Create single logical volumes of multiple physical volumes or entire hard disks
* Add or remove volumes/disk dynamically 
* Increase or decrease size of Logical Volumes (LVs)
* Create snapshots

LVM introduces the concept of Volume Groups (VGs) and Logical Volumes (LVs).

Configuration file: <code>/etc/lvm/[[lvm.conf]]</code>


== Components ==
* <code>[[lvmetad]]</code> [[LVM]] metadata cache daemon

== Basic commands ==
* List Volume Groups:<code>[[vgs]]</code><ref>http://man7.org/linux/man-pages/man8/vgs.8.html</ref>
** <code>[[vgscan]]</code>, <code>[[vgextend]]</code>, <code>[[vgdisplay]]</code>
* List logical volumes: <code>[[lvs]]</code><ref>http://man7.org/linux/man-pages/man8/lvs.8.html</ref>, [[lvdisplay]]
* Resize LV: 
** <code>[[lvresize]]</code>
** <code>[[lvextend]]</code>
** <code>[[lvreduce]]</code>

* Display commands: 
::<code>[[pvdisplay]]</code><ref>http://man7.org/linux/man-pages/man8/pvdisplay.8.html</ref>
::<code>[[lvdisplay]]</code>
::<code>[[vgdisplay]]</code>

* Create commands:  
::<code>[[pvcreate]]</code><ref>http://man7.org/linux/man-pages/man8/pvcreate.8.html</ref>
::<code>[[lvcreate]]</code><ref>http://man7.org/linux/man-pages/man8/lvcreate.8.html</ref>
::<code>[[vgcreate]]</code>
::<code>[[vgreduce]]</code>

* Ls commands: <code>[[pvs]]</code>, <code>[[lvs]]</code><ref>http://man7.org/linux/man-pages/man8/lvs.8.html</ref>, <code>[[vgs]]</code>
* Scan commands: <code>[[pvscan]]</code><ref>http://man7.org/linux/man-pages/man8/pvscan.8.html</ref>, <code>[[vgscan]]</code>
* PV commands: <code>[[pvdisplay]]</code><ref>http://man7.org/linux/man-pages/man8/pvdisplay.8.html</ref>, <code>pvresize</code>, <code>[[pvscan]]</code>, <code>[[pvcreate]]</code> or <code>[[pvcreate]] -vv</code>
* LV commands: <code>[[lvcreate]]</code><ref>http://man7.org/linux/man-pages/man8/lvcreate.8.html</ref>, [[lvconvert]]
* VG commands: <code>[[vgdisplay]]</code>, <code>[[vgcreate]]</code>, <code>[[vgcfgbackup]]</code>, <code>[[vgscan]]</code>
* LVM commands: <code>[[lvm dumpconfig]]</code>

=== Advanced commands ===
* <code>lvchange</code><ref>http://man7.org/linux/man-pages/man8/lvchange.8.html</ref> — Change attributes of the Logical Volume Manager.
* <code>[[lvmdiskscan]]</code>. Deprecated: used <code>[[pvs]]</code>. Scan for all devices visible to LVM2.
* <code>[[lvmdump]]</code> — Create lvm2 information dumps for diagnostic purposes.

== Activities ==
=== Basic ===
# Read StackOverflow LVMs questions: https://superuser.com/questions/tagged/lvm?tab=Votes
# Read Configuring and Managing Logical Volumens in [[RHEL 8]]: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/configuring_and_managing_logical_volumes/index
# Configure an [[Linux Administration/Devices and Filesystems/LVM|LVM]] Volume with an ext File Sytem: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/high_availability_add-on_administration/s1-lvmsetupnfs-haaa

=== Advanced ===
Before doing these exercises make your you have a backup of your data.
# Convert a Linear Device to a [[RAID]] device: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html-single/configuring_and_managing_logical_volumes/index#proc_converting-linear-to-raid-configure-manage-raid
# Read LVM [[Changelog]]: sourceware.org/git/?p=lvm2.git;a=blame;f=WHATS_NEW;hb=9cad26be321844868a904c7b07bebe37be4e0169

== See also ==
* {{LVM}}
* [[linux/mdadm|mdadm]] and [[Linux Administration/Devices and Filesystems/ZFS|ZFS]]
* resize2fs<ref>https://manpages.debian.org/stretch/e2fsprogs/resize2fs.8.en.html</ref> file system resizer  for ext2/ext3/ext4 (resize2fs /dev/mapper/VolGroup-lv_root) (for ext4 only).<ref>https://www.technomenace.com/2014/08/how-to-extend-lvm-on-qcow2-images/</ref>. Code: https://github.com/tytso/e2fsprogs/blob/master/resize/resize2fs.c
* [[DevOps/Ansible|Ansible]] LV module: https://docs.ansible.com/ansible/latest/modules/lvol_module.html#lvol-module
* [[dmsetup]]
* [[UUID]]



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Original Source: https://en.wikiversity.org/wiki/Linux_Administration/Devices_and_Filesystems/LVM

[[Category:Linux]]
[[Category:Storage]]