How to create LVM in Amazon AWS EC2 / CentOS

LVM stands for Logical Volume Manager. With LVM, we can create logical partitions that can span across one or more physical hard drives. First, the hard drives are divided into physical volumes, then those physical volumes are combined together to create the volume group and finally the logical volumes are created from volume group.

To create a LVM, we need to run through the following steps.

1. Select the physical storage devices for LVM
2. Create the Volume Group from Physical Volumes
3. Create Logical Volumes from Volume Group

You create your new volume from the "Volumes" menu in your EC2 management console.

You attach your new volume to your ec2 instance by right clicking the new volume and choose attach.

From the "Attachment Information", you can see where it is being attached, such as "/dev/sdf".

Or you can then see your new volume inside your EC2 instance:

$ cat /proc/partitions

major minor  #blocks  name

202        1    8388608 xvda1

202       80   18874368 xvdf

Select the Physical Storage Devices for LVM – Use pvcreate, pvscan, pvdisplay Commands

$ sudo pvcreate /dev/xvdf

 Physical volume "/dev/sdf" successfully created

You can view physical volumes created using the pvscan command

$ sudo pvscan

 PV /dev/sdf                      lvm2 [18.00 GiB]

 Total: 1 [18.00 GiB] / in use: 0 [0   ] / in no VG: 1 [18.00 GiB]

You can view the list of physical volumes with attributes like size, physical extent size, total physical extent size, the free space, etc., using pvdisplay command as shown below.

$ sudo pvdisplay

 "/dev/sdf" is a new physical volume of "18.00 GiB"

 --- NEW Physical volume ---

 PV Name               /dev/sdf

 VG Name               

 PV Size               18.00 GiB

 Allocatable           NO

 PE Size               0   

 Total PE              0

 Free PE               0

 Allocated PE          0

 PV UUID               tlrKSp-LN51-98jM-HJYp-fuW5-5fme-I1nZRd

Create the Volume Group – Use vgcreate, vgdisplay Commands

$ sudo vgcreate vol_grp1 /dev/sdf

 Volume group "vol_grp1" successfully created

LVM Create: Create Logical Volumes – Use lvcreate, lvdisplay command

$ sudo lvcreate -l +100%FREE  -n logical_vol1 vol_grp1

 Logical volume "logical_vol1" created

vgdisplay command lists the created volume groups.

$  sudo lvdisplay

 --- Logical volume ---

 LV Path                /dev/vol_grp1/logical_vol1

 LV Name                logical_vol1

 VG Name                vol_grp1

 LV UUID                3DcMk6-dGIm-EN0H-x4Ou-WYbD-c3Be-bsxTyS

 LV Write Access        read/write

 LV Creation host, time ip-10-73-133-174, 2014-09-22 17:50:08 +0000

 LV Status              available

 # open                 0

 LV Size                18.00 GiB

 Current LE             4607

 Segments               1

 Allocation             inherit

 Read ahead sectors     auto

 - currently set to     256

 Block device           253:0

$ sudo  mkfs.ext4 /dev/vol_grp1/logical_vol1

mke2fs 1.42.8 (20-Jun-2013)

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

Stride=0 blocks, Stripe width=0 blocks

1179648 inodes, 4717568 blocks

235878 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=4294967296

144 block groups

32768 blocks per group, 32768 fragments per group

8192 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,

4096000

Allocating group tables: done                            

Writing inode tables: done                            

Creating journal (32768 blocks): done

Writing superblocks and filesystem accounting information: done   

$ sudo mkdir /home2

$ sudo mount  /dev/vol_grp1/logical_vol1   /home2

$ df -h

Filesystem                         Size  Used Avail Use% Mounted on

/dev/xvda1                         7.8G  7.6G  130M  99% /

devtmpfs                           281M   20K  281M   1% /dev

tmpfs                              297M     0  297M   0% /dev/shm

/dev/mapper/vol_grp1-logical_vol1   18G   44M   17G   1% /home2