Suresh Dasari
Editor
12 min read | 10 months ago

How to Install and Configure LVM on Centos

How to configure LVM on Linux (centos/Redhat)

LVM stands for Logical Volume Manager. LVM is a tool for logical volume management. LVM can be used to create easy to maintain logical volumes.

LVM has basically three terms, Physical Volume PV, Volume Group VG, Logical Volume LV.

  • PV – It’s a raw hard drive that it initialized to work with LVM, such as /dev/sdb, /dev/sdc, /dev/sdb1 etc.
  • VG – Many PV is combined into one VG. You can create many VGs and each of them has a unique name.
  • LV – You can create many LVs from a VG. You can extend, reduce the LV size on the fly. The LV also has unique names. You format the LV into ext4, zfs, btrfs etc filesystems, mount it and use it as you do other ordinary partitions.

First, we need to check current disk status and for that, you need to run the following command.

[root@localhost ~]# lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0 28.9G  0 disk 
├─sda1   8:1    0    1G  0 part /boot
├─sda2   8:2    0  1.5G  0 part [SWAP]
├─sda3   8:3    0 21.5G  0 part /
sdb      8:16   0 21.2G  0 disk 
sdc      8:32   0 21.2G  0 disk 
sdd      8:48   0 21.2G  0 disk 

 Step 1: create a new Partiton using fdisk tool and select partition type LVM

[root@localhost ~]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0xa37176bf.
Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-44498687, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-44498687, default 44498687): 
Using default value 44498687
Partition 1 of type Linux and of size 21.2 GiB is set
Command (m for help): p
Disk /dev/sdb: 22.8 GB, 22783328256 bytes, 44498688 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
Disk label type: dos
Disk identifier: 0xa37176bf
 Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048    44498687    22248320   83  Linux
Command (m for help): L
 0  Empty           24  NEC DOS         81  Minix / old Lin bf  Solaris        
 1  FAT12           27  Hidden NTFS Win 82  Linux swap / So c1  DRDOS/sec (FAT-
 2  XENIX root      39  Plan 9          83  Linux           c4  DRDOS/sec (FAT-
 3  XENIX usr       3c  PartitionMagic  84  OS/2 hidden C:  c6  DRDOS/sec (FAT-
 4  FAT16 <32M      40  Venix 80286     85  Linux extended  c7  Syrinx         
 5  Extended        41  PPC PReP Boot   86  NTFS volume set da  Non-FS data    
 6  FAT16           42  SFS             87  NTFS volume set db  CP/M / CTOS / .
 7  HPFS/NTFS/exFAT 4d  QNX4.x          88  Linux plaintext de  Dell Utility   
 8  AIX             4e  QNX4.x 2nd part 8e  Linux LVM       df  BootIt         
 9  AIX bootable    4f  QNX4.x 3rd part 93  Amoeba          e1  DOS access     
 a  OS/2 Boot Manag 50  OnTrack DM      94  Amoeba BBT      e3  DOS R/O        
 b  W95 FAT32       51  OnTrack DM6 Aux 9f  BSD/OS          e4  SpeedStor      
 c  W95 FAT32 (LBA) 52  CP/M            a0  IBM Thinkpad hi eb  BeOS fs        
 e  W95 FAT16 (LBA) 53  OnTrack DM6 Aux a5  FreeBSD         ee  GPT            
 f  W95 Ext'd (LBA) 54  OnTrackDM6      a6  OpenBSD         ef  EFI (FAT-12/16/
10  OPUS            55  EZ-Drive        a7  NeXTSTEP        f0  Linux/PA-RISC b
11  Hidden FAT12    56  Golden Bow      a8  Darwin UFS      f1  SpeedStor      
12  Compaq diagnost 5c  Priam Edisk     a9  NetBSD          f4  SpeedStor      
14  Hidden FAT16 <3 61  SpeedStor       ab  Darwin boot     f2  DOS secondary  
16  Hidden FAT16    63  GNU HURD or Sys af  HFS / HFS+      fb  VMware VMFS    
17  Hidden HPFS/NTF 64  Novell Netware  b7  BSDI fs         fc  VMware VMKCORE 
18  AST SmartSleep  65  Novell Netware  b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3 70  DiskSecure Mult bb  Boot Wizard hid fe  LANstep        
1c  Hidden W95 FAT3 75  PC/IX           be  Solaris boot    ff  BBT            
1e  Hidden W95 FAT1 80  Old Minix      
Command (m for help): 8e
8: unknown command
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   g   create a new empty GPT partition table
   G   create an IRIX (SGI) partition table
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)
Command (m for help): p
Disk /dev/sdb: 22.8 GB, 22783328256 bytes, 44498688 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
Disk label type: dos
Disk identifier: 0xa37176bf
Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048    44498687    22248320   83  Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@localhost ~]# partprobe

Do same for /dev/sdc and /dev/sdd also

once it is done, now we will create pv as below

Step 2: Create physical volume

[root@localhost ~]# pvcreate /dev/sdb1 /dev/sdc1 /dev/sdd1
  Physical volume "/dev/sdb1" successfully created.
  Physical volume "/dev/sdc1" successfully created.
  Physical volume "/dev/sdd1" successfully created.

For scanning disks run below command

[root@localhost ~]# lvmdiskscan

To display physical voumes

[root@localhost ~]# pvdisplay

You can list the newly created PVs with

[root@localhost ~]# pvs

Step 3: Create volume group

Now we can create the volume group named “vg00". you can give any other name.

[root@localhost ~]# vgcreate vg00 /dev/sdb1 /dev/sdc1 /dev/sdd1
  Volume group "vg00" successfully created

Now you can list all the vgs with the following command

[root@localhost ~]# vgscan

The following command shows the brief details about the volume group "vg00"

[root@localhost ~]# vgdisplay vg00
  --- Volume group ---
  VG Name               vg00
  System ID             
  Format                lvm2
  Metadata Areas        3
  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                3
  Act PV                3
  VG Size               63.64 GiB
  PE Size               4.00 MiB
  Total PE              16293
  Alloc PE / Size       0 / 0   
  Free  PE / Size       16293 / 63.64 GiB
  VG UUID               MN3eZK-hGxy-J8OD-UUuU-ylCG-HLVJ-dpJO2L

If you wish you can add more PV to an existing vg00 with following command.

vgextend vg00 /dev/sde1

Step 4: Create Logical volume

Use of the following command creates the LV called “data” size of 10 GB in the VG.

-L – Size in the KB/MB/GB.

-l – Size in PE (Physical Extend 1PE=4MB)

-n – name of the LV

[root@localhost ~]# lvcreate -L 10G -n data vg00
  Logical volume "data" created.

you can scan logical volume and display information with below commands

[root@localhost ~]# lvscan
[root@localhost ~]# lvdisplay

Step 5: Create the mount point and mount the new LVM 

 Now make directory for mounting.

[root@localhost ~]# mkdir /test

Before each logical volume can be used, we need to create a filesystem.

[root@localhost ~]# mkfs.ext4 /dev/vg00/data

you can check  BlockID with below command.

[root@localhost ~]# blkid

now mount with /test as follows

[root@localhost ~]# mount /dev/vg00/data /test

verify new disk layout

[root@localhost ~]# df -H
Filesystem             Size  Used Avail Use% Mounted on
/dev/sda3               23G  3.8G   18G  18% /
devtmpfs               637M     0  637M   0% /dev
tmpfs                  653M     0  653M   0% /dev/shm
tmpfs                  653M   11M  643M   2% /run
tmpfs                  653M     0  653M   0% /sys/fs/cgroup
/dev/sda1              1.1G  130M  823M  14% /boot
tmpfs                  131M   13k  131M   1% /run/user/989
tmpfs                  131M     0  131M   0% /run/user/0
/dev/mapper/vg00-data   11G   38M  9.9G   1% /test

Put on /etc/fstab to automount the partition when system starts.

[root@localhost ~]# vi /etc/fstab
###############  Add below line at the end of the file #################
/dev/mapper/vg00-data        /test                   ext4    defaults        0 0

sample output:

[root@localhost ~]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Wed Aug 21 20:30:01 2019
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=a7d9ee27-2cb2-4d85-ae8b-f89ae638887c /                       ext4    defaults        1 1
UUID=e25dcfd8-b259-46cf-92a9-681595f9d2aa /boot                   ext4    defaults        1 2
UUID=4060b8d5-45ff-4c15-8489-a6cf03c13b5e swap                    swap    defaults        0 0
/dev/mapper/vg00-data                     /test                   ext4    defaults        0 0

Thats it! Now we have successfully created LVM.

Step 6: Extend Logical volumes

If you are  running out of space in logical volume then increase it.

Now i want to increase 2GB /dev/mapper/vg00-data as below

[root@localhost ~]# lvextend -L +2G -r /dev/vg00/data
[root@localhost ~]# df -H
Filesystem             Size  Used Avail Use% Mounted on
/dev/sda3               23G  3.8G   18G  18% /
devtmpfs               637M     0  637M   0% /dev
tmpfs                  653M     0  653M   0% /dev/shm
tmpfs                  653M   11M  643M   2% /run
tmpfs                  653M     0  653M   0% /sys/fs/cgroup
/dev/sda1              1.1G  130M  823M  14% /boot
tmpfs                  131M   13k  131M   1% /run/user/989
tmpfs                  131M     0  131M   0% /run/user/0
/dev/mapper/vg00-data   13G   42M   12G   1% /test

 

 

 



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