How to implement Logical Volume Management on Linux

How to configure LVM on Linux

Logical Volume Manager (LVM) is a storage management technology used in Linux and other Unix-like operating systems. It allows users to create, resize, and move logical volumes (LVs) and volume groups (VGs) dynamically without requiring any downtime. With LVM, administrators can abstract physical storage devices and manage them as logical volumes, providing greater flexibility and easier management of storage resources. LVM allows for logical volume snapshots, which are read-only copies of a logical volume that can be used for backups, testing, or other purposes without disrupting the original volume. LVM provides a powerful and flexible solution for managing storage in Linux systems.

The following steps can work on CentOS, AlmaLinux, Rocky and Redhat Linux

1. Install the LVM packages if they are not already installed:

   # yum install lvm2

2. Create a new partition using fdisk or another partitioning tool:

   # fdisk /dev/sdb

3. Set the partition type to Linux LVM (code 8e):

   Command (m for help): t
   
       Partition number (1-4): 1
   
       Hex code (type L to list all codes): 8e
   
       Command (m for help): w

4. Create a physical volume on the new partition:

   # pvcreate /dev/sdb1

   You will see:

   Physical volume "/dev/sdb1" successfully created

Here’s an example of what you will see on the screen during these steps:

[root@localhost ~]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.32.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 
First sector (2048-41943039, default 2048): 
Last sector, +sectors or +size{K,M,G,T,P} (2048-41943039, default 41943039): +2G

Created a new partition 1 of type 'Linux' and of size 2 GiB.

Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'.

Command (m for help): p

Disk /dev/sdb: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x5de74d5c

Device     Boot Start      End  Sectors Size Id Type
/dev/sdb1        2048  4196351  4194304   2G 8e Linux LVM

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

5. Create a volume group using the physical volume:

   # vgcreate my_vg /dev/sdb1

6. Check the volume group information:

   # vgdisplay my_vg

An example output of the command could be:

--- Volume group ---
VG Name               my_vg
System ID             
Format                lvm2
Metadata Areas        1
Metadata Sequence No  1
VG Access             read/write
VG Status             resizable
MAX LV                0
Cur LV                0
Open LV               0
Max PV                0
Cur PV                1
Act PV                1
VG Size               <1.00 GiB
PE Size               4.00 MiB
Total PE              255
Alloc PE / Size       0 / 0   
Free  PE / Size       255 / <1.00 GiB
VG UUID               A94s73-l0Y7-2HrB-lq3B-9XzT-0iQD-4Mq3oI

7. Create a logical volume named my_lv with a size of 512 MiB:

   # lvcreate -L 512M -n my_lv my_vg

8. Check the logical volume information:

   # lvdisplay my_vg/my_lv

An example output of the command could be:

--- Logical volume ---
LV Path                /dev/my_vg/my_lv
LV Name                my_lv
VG Name                my_vg
LV UUID                t7mZ9X-DdF7-69jP-MCvL-jg90-wQeL-IdwJhB
LV Write Access        read/write
LV Creation host, time localhost, 2021-10-25 09:44:21 +0000
LV Status              available
# open                 0
LV Size                512.00 MiB
Current LE             128
Segments               1
Allocation             inherit
Read ahead sectors     auto
- currently set to     8192
Block device           253:1

9. Create a file system on the logical volume:

   # mkfs.ext4 /dev/my_vg/my_lv

10. Create a mount point:

    # mkdir /mnt/my_lv

11. Mount the logical volume:

    # mount /dev/my_vg/my_lv /mnt/my_lv

12. Verify that the logical volume is mounted:

    # mount | grep /mnt/my_lv

An example output of the command could be:

/dev/mapper/my_vg-my_lv on /mnt/my_lv type ext4 (rw,relatime)

13. Edit the /etc/fstab file to automatically mount the logical volume at boot time:

    # vi /etc/fstab

Add the following line at the end of the file:

/dev/my_vg/my_lv /mnt/my_lv ext4 defaults 0 0

Save and exit the file.

That's it! The logical volume is now mounted and will automatically mount at boot time.