How to Create LVM in Linux

How to Create LVM in Linux

LVM (LogicalVolumeManager) allows administrators to create meta devices in Linux that provide an abstraction layer between a file system and the physical storage that is used underneath. The meta devices (on which file systems are placed) are logical volumes, which use storage from storage pools called volume groups. A volume group is provisioned with one or more physical volumes which are the true devices on which the data is stored.

Physical Volume = PV

Volume Group = VG

Logical Volume  = LV

The best analogy I can come up with for explaining LVM is a SAN.  (Storage Area Network) abstracts the idea of individual hard drives and allows you to carve out “chunks” of space to use as drives.  LVM is sort of like that, but for an individual system rather than an entire network.

Let’s say you have two hard drives, /dev/sdb and /dev/sdc. With LVM, any block device can be used as a physical volume (PV).
Once you have the block devices you want to add to your volume group. To do that, use the pvcreate command :

Step 1 : Create physical volume :

pvcreate /dev/sdb
pvcreate /dev/sdc

linux@ap2v:~$ sudo pvdisplay
  --- Physical volume ---
  PV Name               /dev/sdb
  VG Name               
  PV Size               10.4 GiB / not usable 3.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              4994
  Free PE               4994
  Allocated PE          0
  PV UUID               SRKAXh-EpYr-r2td-g0gA-31RA-fnfz-3qqGrO
  --- Physical volume ---
  PV Name               /dev/sdc
  VG Name               
  PV Size               10.4 GiB / not usable 3.00 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              4994
  Free PE               4994
  Allocated PE          0
  PV UUID               t2cKru-IwMy-I8re-ADp2-vzFF-Tvh5-O4zMhI

linux@ap2v:~$ sudo pvscan
  PV /dev/sdb         lvm2 [10.4 GiB]
  PV /dev/sdc         lvm2 [10.4 GiB]
  Total: 2 [20.8 GiB] / in use: 0 [0 ] / in no VG: 2 [20.8 GiB]

Step 2 : Create the Volume Group :
You don’t currently have any volume groups, so create one using the two physical volumes :

vgcreate my_volume_group /dev/sdb /dev/sdc

You’ve created a volume group named my_volume_group using the physical volumes /dev/sdb and /dev/sdc. As with the physical volumes, if you want to check the current state of LVM Volume Groups on your system, type vgdisplay to get a listing :

linux@ap2v:~$ sudo vgdisplay
  --- Volume group ---
  VG Name               my_volume_group
  System ID             
  Format                lvm2
  Metadata Areas        2
  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                2
  Act PV                2
  VG Size               20.8 GiB
  PE Size               4.00 MiB
  Total PE              9988
  Alloc PE / Size       0 / 0 GiB
  Free  PE / Size       9988 / 20.8 GiB
  VG UUID               oVYiY6-bQp9-4CVO-QgrN-LGgB-1umR-ebJQo4

Step 3 : Create the Logical Volumes :
You get /dev/sda, /dev/sdb and so on. When you create logical volumes, To create your logical volumes, type :

linux@ap2v:~$ sudo lvcreate -L 5G -n 5gig my_volume_group
  Logical volume "5gig" created

linux@ap2v:~$ sudo lvdisplay
  --- Logical volume ---
  LV Path                /dev/my_volume_group/5gig
  LV Name                5gig
  VG Name                my_volume_group
  LV UUID                3MxOB0-ce5o-yvBD-YORT-52qV-j8HJ-oDru2G
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                5.0 GiB
  Current LE             5753
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           252:0

Once you’ve successfully created your logical volume. Then mount filesystem as your /home directory

linux@ap2v:~$ sudo mkfs.ext4 /dev/my_volume_group/5gig
linux@ap2v:~$ sudo mount -t ext4 /dev/my_volume_group/5gig /home

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