In this post we will give you a crash course on Linux LVM (Logical Volume Manager). This post will cover the most used LVM commands in a Linux Admin life.
Before we start first let's go through the concepts.
Physical Volumes (PVs): Storage devices (physical hard disks, partitions, RAID arrays etc.) provides raw storage
Volume Groups (VGs): Combine multiple PVs to create a group. They can be mirror or concatenation of PVs.
Logical Volumes (LVs): Create smaller volumes from the Volume Group(VG) as per your size requirement. You can can use the LVs to create filesystem on them.
Below commands are for RHEL 7.
All the below commands will require root access. You can either run them with sudo or switch to root user as mentioned below.
sudo su -
Install LVM
[root@cloudvedas ~]# yum install lvm2*
Check LVM version
[root@cloudvedas ~]# lvm version
Label the new disk and bring it under LVM using pvcreate
Create PV (Physical Volume)
[root@cloudvedas ~]# pvcreate /dev/sdb1
Show PV
[root@cloudvedas ~]# pvs /dev/sdb1
Create VG (Volume Group)
[root@cloudvedas ~]# vgcreate cvsvg /dev/sdb1
Show VG
[root@cloudvedas ~]# vgs cvsvg
Display VG
[root@cloudvedas ~]# vgdisplay cvsvg
Extend VG
[root@cloudvedas ~]# vgextend cvsvg /dev/sdb2
Create LV (Logical Volume)
[root@cloudvedas ~]# lvcreate -L 500M cvsvg -n cldvdsvol1
Display LV
[root@cloudvedas ~]# lvdisplay /dev/cvsvg/cldvdsvol1
Create mirror volume
lvcreate -L 100M -m1 -n cvmirrorvol1 cvsvg
Create striped volume
[root@cloudvedas ~]# lvcreate -L 50M -i 3 -I 64 -n stripevol cvsvg
Here
-i|--stripes (Number of disks in stripe)
-I|Stripe size
Extend LV
lvextend -L +20M /dev/cvsvg/stripevol
De-activate volume
lvchange -an /dev/cvsvg/stripevol
Activate volume
lvchange -ay /dev/cvsvg/stripevol
Remove LV
Ensure filesystem is unmounted before running this
lvremove /dev/cvsvg/stripevol
Create filesystem
mkfs -t ext4 /dev/cvsvg/cldvdsvol1
Create directory
mkdir /CVFS1
Mount filesystem
mount /dev/cvsvg/cldvdsvol1 /CVFS1
All the available LVM commands
[root@cloudvedas ~]# lvm help
Available lvm commands:
Use 'lvm help <command>' for more information
devtypes Display recognised built-in block device types
dumpconfig Dump configuration
formats List available metadata formats
help Display help for commands
lvchange Change the attributes of logical volume(s)
lvconvert Change logical volume layout
lvcreate Create a logical volume
lvdisplay Display information about a logical volume
lvextend Add space to a logical volume
lvmchange With the device mapper, this is obsolete and does nothing.
lvmdiskscan List devices that may be used as physical volumes
lvmsadc Collect activity data
lvmsar Create activity report
lvreduce Reduce the size of a logical volume
lvremove Remove logical volume(s) from the system
lvrename Rename a logical volume
lvresize Resize a logical volume
lvs Display information about logical volumes
lvscan List all logical volumes in all volume groups
pvchange Change attributes of physical volume(s)
pvresize Resize physical volume(s)
pvck Check the consistency of physical volume(s)
pvcreate Initialize physical volume(s) for use by LVM
pvdata Display the on-disk metadata for physical volume(s)
pvdisplay Display various attributes of physical volume(s)
pvmove Move extents from one physical volume to another
pvremove Remove LVM label(s) from physical volume(s)
pvs Display information about physical volumes
pvscan List all physical volumes
segtypes List available segment types
tags List tags defined on this host
vgcfgbackup Backup volume group configuration(s)
vgcfgrestore Restore volume group configuration
vgchange Change volume group attributes
vgck Check the consistency of volume group(s)
vgconvert Change volume group metadata format
vgcreate Create a volume group
vgdisplay Display volume group information
vgexport Unregister volume group(s) from the system
vgextend Add physical volumes to a volume group
vgimport Register exported volume group with system
vgmerge Merge volume groups
vgmknodes Create the special files for volume group devices in /dev
vgreduce Remove physical volume(s) from a volume group
vgremove Remove volume group(s)
vgrename Rename a volume group
vgs Display information about volume groups
vgscan Search for all volume groups
vgsplit Move physical volumes into a new or existing volume group
version Display software and driver version information
[root@cloudvedas ~]#