How To Create LVM Partition In Linux | RHEL 7

Hi Guys, In this post I will show you that how you can add a LVM partition in your Linux system. LVM have great flexibility over general partition types.You can easily manipulate, manage , add , remove, extend the partition even you can merge two disk partitions with in a single LVM partitions. however there are some drawbacks using LVM. One big disadvantage of using LVM is that it makes system slower up-to 40% and It creates complexity when disks gets corrupted.Its better to use LVM partitions for storage purpose not for system partitions.Below I have explained step by step that how you can create LVM partition.

Adding New Disk or Check Free Space In Existing Disk

First of all you have to check the free disk space available in your existing disk. For this you can run below command in your Linux system.
lsblk >> For all mounted disks

or 

lsblk /dev/sdX >> (replace X with disk letter)

checking free space in your disk drive

If you want to see more details about your mounted disk, run below command.

parted /dev/sdX unit MiB print free (replace X with disk letter)

checking free space in your disk drive

If you don't have enough free space in your disk to create a new partition then add a disk. Below is the screenshot of virtual machine in which I am adding a new disk. First shutdown your machine > select your virtual machine > open setting option > select storage > on storage device , under Controller SATA > click the + sign of disk storage > create the new disk > type the size > ok . 

Once you sure that you have enough space to create a new partition, we can go further for next steps.

Create Partitions In Your Disk With LVM File System

Below are the steps in order to create a new partition with your existed mounted disk or in new drive. Below example is for new drive. 

i) fdisk /dev/sdb

ii) press m for menu

iii) press 'n' key for new partition

iv) select option 'p' or 'e' from keyboard , where p is for primary partition and e is for extended.

Note: Linux can support only four primary partition for MBR partiton table & 128 primary partitions for GPT table.

creating partition with fdisk

v) type the partition number or just press enter for default value.

vi) type the first sector value or just press enter for default value.

vii) type the last sector value or you can type the required size for your partition.

For example: +500M will create new partition with 500MB space. use G or K in order to create size in GB or KB.

viii) once you hit enter , now press 'w' to write the change into disk.

creating partition with fdisk

Now you have successfully created the new partition for your drive. Now we can go to our next step.

Change Your Disk Partition Type Linux To LVM

In order to create LVM partition first we have to change our disk partition type Linux to Linux LVM , use below commands to change the partitions to LVM.

i) fdisk /dev/sdX (replace X with your disk letter )

ii) Press 't' to change the partition type

iii) Select your partition number ( remember (v) line of previous step )

creating partition with fdisk

iv) press '8e' in order to change  your partition to LVM or you can press 'L' in order to check the list of all partitions.

v) press 'w' key to write the changes to system.

creating partition with fdisk

Now you have successfully change the partition type. you can check the changes by command fdisk -l /dev/sdX

checking disk partitions

Creating Physical Volume: After creating the LVM partition successfully  now we have to create the physical partitions for our LVM. Follow the below steps to create physical partition.

i) run command as show below

pvcreate /dev/sdXN (change the X with the drive letter and N with the partition number )

creating PV

as you can see in above picture that I have create two physical volume together. if you also have create two LVM partitions you can also do the same.

ii) run the below command to check if we successfully created the physical volume or not.

pvdisplay /dev/sdXN(change the X with the drive letter and N with the partition number )

display info about PV

Now we can move to our next step.

Create Volume Group: Now we have to create a volume group for our LVM. run the below commands to create volume group. you can give any name for your volume group.

i) vgcreate "name of the group" /dev/sdXN (change the X with the drive letter and N with the partition number )

ii) Check the volume group created successfully or not with below command.

vgdisplay "name of the group"

Creating VG & Display VG info

Create Logical Volume: Now we have to create the logical volume partition where we will actually save our data after mounting that. run the below commands to create logical volume for LVM.

i) lvcreate -L 500 -n 'name of LV' 'name of your VG'  ( where -L for size in MB , -n option for name of LV)

creating LV partition

This command will create a new logical volume with 500M & with given name.

ii) To verify our LV run below command.

lvdisplay 'name of LV'

display the LV info

Format Newly Create LV : Before mount our LV , we have to format this with any supported file system. run the below command to do the same. There are couple of file system available. Choose as per your choice and preference.

i) mkfs.xfs /dev/name of VG /name of LV

format LV with mkfs command

Mounting LV Partition & Using : To use logical volume partition , you have to mount that partition into your system.You can mount your partition in two ways one is temprory & another is permanent.Both ways are mention below.

Temporary Mount :

i) First create a folder where you want to mount your LVM partition or use the default /mnt path with below commands.

-mkdir /path/to/create/a/folder

-mount /mnt

ii) Then mount the partition to that folder or path.

mount /dev/volume_group_name/logical_volume_name   /path_to_mount

mount LV under /mnt for temporary

Permanent Mount:

i) run command : blkid  It will show the block id for the mounted devices

UUID check with blkid

ii) copy the UUID of mounted logical volume.

iii) open the /etc/fstab file with any text editor e.g vim, nano. and add the below entery in it.

UUID=7acc701c-030f-4559-ae2d-0d4dac78b7e9 /mnt  xfs     defaults 0 0

- Where UUID code copied from blkid 

- /mnt is folder path where we are mounting that LVM partition

- xfs is the file system type

-  default is for mount option

- 0 for dump check disable

- 0 for file system check disable

iv) save the file.

last line entry of LV in fstab file last

v) Now active the mount partitions with below command

mount -a 

activate all partitions which you just mounted

partprobe

to update kernel with partition info

vi) verify the mounted partition.

logical volume /database-storage has been mounted under /mnt folder

That's All

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