I have been trying to get my head around the basic features of LVM for my LPIC-1 Exam 101. I thought I would share my revision notes with the Steemit community, I have been working with Centos 7.

Physical Volumes

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pvdisplay – displays physical volumes

pvcreate – creates a physical volume

lsblk – lists block devices

Begin by using lsblk to show physical devices.

lsblk

In this example, we’ll say sda and sdb are listed. The below command will create a physical volume.

pvcreate /dev/sdb

Next, you want to display the physical volumes to see if it has been created successfully.

pvdisplay

Now you should see the new physical volume 'sdb'.

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Volume Groups

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vgdisplay – displays volume groups

vgcreate – creates a volume group

Next, you want to display the volume groups to see if it has been created successfully.

vgdisplay

Now you should see the new volume group 'testvg'.

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Logical Volumes

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lvdisplay – displays logical volumes

lvcreate – creates a logical volume

I ran the below command to create a logical volume called ‘mylv’ which is located in the volume group ‘testvg’. I used the -l 100% to use 100% of the volume group.

lvcreate -l 100%VG -n mylv testvg

Next, you want to display the logical volumes to see if it has been created successfully.

lvdisplay

Now you should see the new volume group 'mylv'.

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Creating a filesystem and mounting

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The below command will create a file system using ext4 on the logical volume ‘mylv’ that was created previously.

mkfs.ext4 /dev/testvg/mylv

Next, I made a directory to mount the logical volume with the below command.

mkdir /mnt/media

I then mounted the logical volume to /mnt/media

mount /dev/testvg/mylv /mnt/media

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Editing fstab

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For the volume to automount on reboot you will need to edit fstab.

cd /etc/

vi fstab

Within ‘fstab’ you will need to specify some options regarding the new logical volume and it’s mount point. For this example, I added the below.

/dev/testvg/mylv /mnt/media ext4 defaults 0 0

You can read more about ‘fstab’ at the below link;

https://community.linuxmint.com/tutorial/view/1513

I hope this is of use to some people, it certainly helped me break down the LVM hierarchy and how to create a file system in Linux.

Liam AKA Gadgie