How to Setup Linux LVM (Logical Volume Manager) Using Pvcreate, Vgcreate, Lvcreate with Example

In this article, we are going to learn How to Setup Linux LVM (Logical Volume Manager) using pvcreate, vgcreate, lvcreate commands. LVM stands for Logical Volume Manager OR Logical Volume Management. As its name Linux LVM used to Manage the Logical Volumes by Extend, Resize, Reduce, Rename and so many other features.

Why we should use Logical Volume Manager (LVM)?

As we already discussed Linux LVM is used to Extend the Logical Volume Partition, Reduce the Partition, Resize the Partition, and so on. Now you might be thinking that Where we would be required to Extend the Partition. Let me give you a quick Example so that your concept will get more clear toward Logical Volume Manager (LVM).

Example of a Normal Harddisk Server Setup (Without LVM) :

Suppose You have a server in your office whose Harddisk size let’s say about 500 GB and all users are storing their data in that server. One day you came to know that the Harddisk got full and you have no space left for storing more data any further. In that case, you have two options to make space available for user i.e either delete unwanted data OR move the data manually to some different hard disk. But you have no options to Increase or extend the disk space in case of the normal hard disk.

Example of Linux LVM Configured Server :

Now let’s take the above scenario with Linux LVM configured Server. In this case, if your 500 GB harddisk got full then you can take a New Harddisk and just connect it and Extend your current Partition Live without losing any data and also without any downtime. You don’t even require to shut down or restart the server during harddisk extend process.

Advantages of Linux LVM (Logical Volume Manager) :

Linux LVM (Logical Volume Manager) capable of performing below tasks :

  • Extend the Physical Volume, Volume Group, Logical Volume Partition’s
  • Reduce the Physical Volume, Volume Group, Logical Volume Partition’s
  • Resize the Physical Volume, Volume Group, Logical Volume Partition’s
  • Take a snapshot of Logical Volume using Linux LVM Snapshot…and so on.

How to Setup Linux LVM (Logical Volume Manager) Using Pvcreate, Vgcreate, Lvcreate with Example

Follow the below Steps to Configure Linux LVM (Logical Volume Manager) :

To configure Linux LVM we need at least a Physical Harddisk or a Partition. Here I have 3 Harddisk’s i.e : /dev/sdb/dev/sdc/dev/sdd with size 2 GB each.

[[email protected] ~]# fdisk -l   # To List Partition Table

Disk /dev/sda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000817a9

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          39      307200   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              39        2350    18566144   83  Linux
/dev/sda3            2350        2611     2097152   82  Linux swap / Solaris

Disk /dev/sdb: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/sdc: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000


Disk /dev/sdd: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

The Three major steps we have to follow to Setup a Logical Volume Manager (LVM). The Steps are :

  • Physical Volume:  Prepare the Physical Harddisk’s some way so that Linux LVM can understand the Device and can be used to configure Volume Group and Logical Volumes is call as Physical Volume.
  • Volume Group: Combination of Multiple Physical Volumes is called Volume Group.
  • Logical Volume: We can create Partitions out of Volume Group to store data is called a Logical Volume. Logical Volumes are the same as we are using normal Disk Partitions.

Create Physical Volume using pvcreate (PV)

First, we have to prepare the Physical Harddisk’s for Linux LVM so that Linux LVM can understand that yes these Harddisks are now prepared and can be used to Configure Logical Volume Manager. For that, we have to convert Physical Harddisks as a Physical Volume. To do so we can use the command pvcreate.  Here I am creating my First Physical Volume using my Harddisk /dev/sdb. Refer to the command below.

Syntax: pvcreate [Physical Harddisk]

[[email protected] ~]# pvcreate /dev/sdb   # Create Physical Volume
  Physical volume "/dev/sdb" successfully created

As you can see above we created physical volume successfully. To check the details of Physical Volume use the command pvdisplay.

You can use only pvdisplay command to show all available Physical Volumes’s in the system.

[[email protected] ~]# pvdisplay   # Check Physical Volume Details

OR you can mention particular physical volume to check the details.

[[email protected] ~]# pvdisplay /dev/sdb   # Check Physical Volume Details
  "/dev/sdb" is a new physical volume of "2.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb
  VG Name               
  PV Size               2.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               Mefmtv-XiDU-FWAo-KTgM-t54Z-7ZCE-n8WQDj

Where : 

  • PV Name: Physical Harddisk Name
  • VG Name: Volume Group Name
  • PV Size: Physical Volume Size
  • Allocatable: The amount of Space we can allocate, Currently It’s NO.
  • PE Size: PE stands for Physical Extent. Normally the size of the Physical Extent is 4 MB. Here It’s 0 as we haven’t created any Volume Group out of this Physical Volume. Once We create Volume Group from this Physical Volume then PE SizeTotal PEFree PE, and Allocated PE options will get an update.
  • Total PE: Total available Physical Extents.
  • Free PE: Remaining Physical Extents.
  • Allocated PE: Already Allocated Physical Extent to Volume Group.

Note: The Physical Extent (PE) details are updated in Physical Volume only after create a Volume Group out of it.

Below I have explained what is Physical Extent and How to calculate it.

We have two more Physical Harddisk’s i.e. /dev/sdc and /dev/sdd which need to be configured as Physical Volume. So follow the below commands to so.

[[email protected] ~]# pvcreate /dev/sdc
  Physical volume "/dev/sdc" successfully created
  
[[email protected] ~]# pvcreate /dev/sdd
  Physical volume "/dev/sdd" successfully created

You can also use pvs command to check the quick short summary of all available Physical Volumes. vgs referred to as Volume Group Summery.

[[email protected] ~]# pvs   # Check available Physical Volumes
  PV         VG   Fmt  Attr PSize PFree
  /dev/sdb        lvm2 a--  2.00g 2.00g
  /dev/sdc        lvm2 a--  2.00g 2.00g
  /dev/sdd        lvm2 a--  2.00g 2.00g

Also Read – How to Configure Linux LVM (Logical Volume Manager) Using Software RAID 5

Create Volume Group (VG) using vgcreate

So we have completed our first step and ready with Physical Volumes. Now let’s move to our next step and create Volume Groups by using vgcreate command.

Syntax: vgcreate [Name of Volume Group] [Physical Volumes] 

[[email protected] ~]# vgcreate vgroup001 /dev/sdb /dev/sdc /dev/sdd   # Create Volume Group
  Volume group "vgroup001" successfully created

To check the details of Volume Group you can use the command vgdisplay.

[[email protected] ~]# vgdisplay   # Check the details of Volume Group
  --- Volume group ---
  VG Name               vgroup001
  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               5.99 GiB
  PE Size               4.00 MiB
  Total PE              1533
  Alloc PE / Size       0 / 0   
  Free  PE / Size       1533 / 5.99 GiB
  VG UUID               xn4b80-1CeV-KYJu-1x6Z-ipTQ-2fSZ-axLx3D

Where :

  • VG Name: Name of the Volume Group
  • Format: Linux LVM (Logical Volume Manager) Version 2
  • VG Access: Volume Group can be Read and Writable
  • VG Status: Volume Group can be Resizable
  • MAX LV: You can create an unlimited number of Logical Volumes in this Volume Group till available Physical Extent (PE).
  • Cur LV: Currently created Logical Volumes is 0
  • Max PV: You can add an unlimited number of Physical Volumes to this Volume Group.
  • Cur PV: Currently we have 3 Physical Volumes assigned this Volume Group.
  • Act PV: Active Physical Volumes are 3.
  • VG Size: Total Size of the Volume Group.
  • PE Size: As I already discussed above the size of Physical Extent (PE) is 4 MB.
  • Alloc PE / Size: Allocated Physical Extent. Here we haven’t allocated any of PE to Logical Volume. and the Volume Group is completely free to use and create Logical Volumes.
  • Free PE / Size : The available Physical Extent (PE) / Size.

Now let’s discuss What is PE (Physical Extent)?

Physical Volume is divided into small pieces of size is called a Physical Extent. For example Here our Volume Group vgroup001 has 1533 PE means, the Physical Volume is divided into 1533 pieces of Physical Extents. Normally the size of a single PE is 4 MB. We can calculate the Physical Extent to find the size of the Volume Group. The calculation would be something like as shown below.

Total Number of PE: 15331 PE: 4 MBSo the size of the Volume Group is: 1533*4 = 6132MB (5.99 GB)

The size of the PE (Physical Extents) is the same as LE (Logical Extents).

To check quick short details of Volumes Groups you can use vgs command. vgs Referred to as Volume Group Summary

[[email protected] ~]# vgs   # Check Volume Group Details
  VG        #PV #LV #SN Attr   VSize VFree
  vgroup001   3   0   0 wz--n- 5.99g 5.99g

Now as we created Volume Groups out of our Physical Volumes, let’s check what all changes happened to our Physical Volumes.

As I explained earlier after creating volume groups out of physical volume the PE (Physical Extent) details will get an update. Refer to the sample output below.

[[email protected] ~]# pvdisplay   # Check Physical Volume Details
  --- Physical volume ---
  PV Name               /dev/sdb
  VG Name               vgroup001
  PV Size               2.00 GiB / not usable 4.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              511
  Free PE               511
  Allocated PE          0
  PV UUID               Mefmtv-XiDU-FWAo-KTgM-t54Z-7ZCE-n8WQDj
   
  --- Physical volume ---
  PV Name               /dev/sdc
  VG Name               vgroup001
  PV Size               2.00 GiB / not usable 4.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              511
  Free PE               511
  Allocated PE          0
  PV UUID               Sq28cI-hNH2-k0Y5-rDOA-GfXi-PWRQ-fjcpYY
   
  --- Physical volume ---
  PV Name               /dev/sdd
  VG Name               vgroup001
  PV Size               2.00 GiB / not usable 4.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              511
  Free PE               511
  Allocated PE          0
  PV UUID               HAl141-kQj9-sZyO-v5t2-xpzn-ZPAx-r4Lfkg

As you can see above all Physical Volumes updated with PE (Physical Extent). and all Physical Extent and Size of Physical Volumes are free to create Logical Volumes.

Check quick short details of Physical Volume.

[[email protected] ~]# pvs
  PV         VG        Fmt  Attr PSize PFree
  /dev/sdb   vgroup001 lvm2 a--  2.00g 2.00g
  /dev/sdc   vgroup001 lvm2 a--  2.00g 2.00g
  /dev/sdd   vgroup001 lvm2 a--  2.00g 2.00g

Create Logical Volumes using lvcreate

We have created Physical Volumes and Volume Group. Now it’s time to create Logical Volume and use that logical volume to store data. Logical Volumes are like normal partitions.

So to create Logical Volume we can use lvcreate command. The syntax to create Logical Volume is :

Syntax : lvcreate -L [Size] -n [Name of the Logical Volume] Volume Group

Here I am creating my first logical volume with size 3 GB with name lvolume001 from Volume Group vgroup001.

[[email protected] ~]# lvcreate -L 3G -n lvolume001 vgroup001  # Create Logical Volume
  Logical volume "lvolume001" created

To check the Logical Volume details use the command lvdisplay.

[[email protected] ~]# lvdisplay   # Check details of Logical Volume
  --- Logical volume ---
  LV Path                /dev/vgroup001/lvolume001
  LV Name                lvolume001
  VG Name                vgroup001
  LV UUID                kEpMd5-PKhi-2S5W-T8p4-cW1S-dfFS-RR9jB9
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2017-06-07 09:07:42 -0700
  LV Status              available
  # open                 0
  LV Size                3.00 GiB
  Current LE             768
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0

You can also quick details of Logical Volumes using lvs command. lvs referred to as Logical Volume Summary.

[[email protected] ~]# lvs
  LV         VG        Attr       LSize Pool Origin Data%  Move Log Cpy%Sync Convert
  lvolume001 vgroup001 -wi-a----- 3.00g                                             

After created the first Logical Volume let’s check what changes happened to our Volume Group using vgdisplay command.

As you can see below the total Physical Extent of the volume group is 5.99 GB and the total Physical Extent is  1533 out of which we create a Logical Volume of size 3 GB. so Now available free space is 2.99 GB and Available Physical Extent is 765.

Available Free Space and PE are highlighted in Blue Color and Utilized Space and PE is highlighted in Red color.

[[email protected] ~]# vgdisplay 
  --- Volume group ---
  VG Name               vgroup001
  System ID             
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               0
  Max PV                0
  Cur PV                3
  Act PV                3
  VG Size               5.99 GiB
  PE Size               4.00 MiB
  Total PE              1533
  Alloc PE / Size       768 / 3.00 GiB
  Free  PE / Size       765 / 2.99 GiB
  VG UUID               xn4b80-1CeV-KYJu-1x6Z-ipTQ-2fSZ-axLx3D

Now let’s create another Logical Volume by using the remaining space of Volume Group. as you can see above currently we have 2.99 GB of Space. If you want to know the exact available size then just calculate by using the Available Physical Extent. The calculation would be something like this :

Available PE: 765PE Size (Size of a single PE) : 4 MB So…Total Remaining Size is: 765*4=3060 MB

To create our second Logical Volume using the below command. Here I am creating the Second Logical Volume with name lvolume002.

[[email protected] ~]# lvcreate -L 3060M -n lvolume002 vgroup001
  Logical volume "lvolume002" created

Now again check the Volume Group details. As you can see below now we have utilized all PE and Size of the Volume Group and cant create any further Logical Volumes.

Note: If you want to create more Logical Volumes you have to add a new physical hard disk to physical volume then need to extend the volume group.

[[email protected] ~]# vgdisplay 
  --- Volume group ---
  VG Name               vgroup001
  System ID             
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               0
  Max PV                0
  Cur PV                3
  Act PV                3
  VG Size               5.99 GiB
  PE Size               4.00 MiB
  Total PE              1533
  Alloc PE / Size       1533 / 5.99 GiB
  Free  PE / Size       0 / 0   
  VG UUID               xn4b80-1CeV-KYJu-1x6Z-ipTQ-2fSZ-axLx3D

To check all available Volume Groups follow the below command.

[[email protected] ~]# lvs
  LV         VG        Attr       LSize Pool Origin Data%  Move Log Cpy%Sync Convert
  lvolume001 vgroup001 -wi-a----- 3.00g      # Logical Volume 1                                       
  lvolume002 vgroup001 -wi-a----- 2.99g      # Logical Volume 2                                      

OR for complete descriptive details, you can use the below command.

[[email protected] ~]# lvdisplay

Now we are all set to store data on logical volumes. For that, we have to create a file system in Logical Volume by formatting it like we usually create during normal partition creation. So here I am formatting the first logical volume i.e. lvolume001 by with the ext4 file system. Refer to the command below.

[[email protected] ~]# mkfs.ext4 /dev/vgroup001/lvolume001  # Format the Logical Volume
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
196608 inodes, 786432 blocks
39321 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=805306368
24 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376, 294912

Writing inode tables: done                            
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 22 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

Then just create a directory for mount the Logical Volume.

[[email protected] ~]# mkdir /lvm

For manual mounting just refer the below command.

[[email protected] ~]# mount /dev/vgroup001/lvolume001 /lvm/

Confirm the mounted device using the below command.

[[email protected] ~]# df -h
Filesystem                        Size  Used Avail Use% Mounted on
/dev/sda2                          18G  2.5G   15G  16% /
tmpfs                             935M  228K  935M   1% /dev/shm
/dev/sda1                         291M   39M  238M  14% /boot
/dev/mapper/vgroup001-lvolume001  3.0G   69M  2.8G   3% /lvm

For permanent mounting, you have to create an entry in /etc/fstab file. So do the below-highlighted entry in your /etc/fstab file.

[[email protected] ~]# nano /etc/fstab 

/dev/vgroup001/lvolume001 /lvm            ext4    defaults        0 0

Where : 

  • /dev/vgroup001/lvolume001 – Logical Volume Path/Name
  • /lvm : Mount Point
  • ext4: File System

To refresh all the mount points refer to the below command.

[[email protected] ~]# mount -a

[[email protected] ~]# df -h
Filesystem                        Size  Used Avail Use% Mounted on
/dev/sda2                          18G  2.6G   15G  16% /
tmpfs                             935M  228K  935M   1% /dev/shm
/dev/sda1                         291M   39M  238M  14% /boot
/dev/mapper/vgroup001-lvolume001  3.0G   69M  2.8G   3% /lvm

That’s all, In this article, we have explained the How to Setup Linux LVM (Logical Volume Manager) Using Pvcreate, Vgcreate, Lvcreate with Example. I hope you enjoy this article. If you like this article, then just share it. If you have any questions about this article, please comment.

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