Linux RHCSA Part 9 - LVM - Logical Volume Manager - Creating a logical volume

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Creating a logical volume step by step. We select the disk on which the volume will be created and initialize it for use as a physical volume.

Step 1 - Initialize the disk

# pvcreate /dev/hdb
Physical volume “/dev/hdb” successfully created

Step 2 - Verify that the physical volume was created correctly

# pvdisplay /dev/hdb
“/dev/hdb” is a new physical volume of “8.00 GiB”
-- NEW Physical volume --
PV Name /dev/hdb
VG Name
PV Size 8.00 GiB
Allocatable NO
PE Size (KByte) 0
Total PE 0
Free PE 0

Allocated PE 0
PV UUID QlCLgF-esaN-5PvR-PWWV-D6jZ-O207-rHg90j


Step 3 - Create a volume group

# vgcreate vg_group01 /dev/hdb
Volume group “vg_group01” successfully created

Step 4 - Verify the creation of the volume group

# vgdisplay -v vg_group01
Using volume group(s) on command line
Finding volume group “vg_group01”
-- Volume group --
VG Name vg_group01
System ID
Format lvm2
Metadata Areas 1
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 1
Act PV 1
VG Size 8.00 GiB
PE Size 4.00 MiB
Total PE 2047
Alloc PE / Size 0 / 0
Free PE / Size 2047 / 8.00 GiB
VG UUID IvjXga-898Y-1vCC-azRt-pszL-PeWR-E5athz
-- Physical volumes --
PV Name /dev/sdb
PV UUID B0K2qH-0UF4-gphE-MLi3-RFXH-HEP9-9FMbA9
PV Status allocatable
Total PE / Free PE 2047 / 2047


Step 5 - Create a partition (logical volume) with a size of 3 GB

# lvcreate -L 3000 vg_group01
Logical volume “lvol0” created

Step 6 - Verify that the volume has been created.

# lvdisplay vg_group01
-- Logical volume --
LV Name /dev/vg_group01/lvol0
VG Name vg_group01
LV UUID mk9dJM-3qt7-ypbC-nsks-I8Gh-9V3d-4BNE6s
LV Write Access read/write
LV Status available
# open 0
LV Size 2.93 GiB
Current LE 750
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2

Step 7 - Display detailed information about the volume group and check for changes after adding the logical volume

# vgdisplay -v vg_group01
Using volume group(s) on command line
Finding volume group “vg_group01”
-- Volume group --
VG Name vg_group01
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 8.00 GiB

PE Size 4.00 MiB
Total PE 2047
Alloc PE / Size 750 / 2.93 GiB
Free PE / Size 1297 / 5.07 GiB
VG UUID IvjXga-898Y-1vCC-azRt-pszL-PeWR-E5athz
-- Logical volume --
LV Name /dev/vg_group01/lvol0
VG Name vg_group01
LV UUID mk9dJM-3qt7-ypbC-nsks-I8Gh-9V3d-4BNE6s
LV Write Access read/write
LV Status available
# open 0
LV Size 2.93 GiB
Current LE 750
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2
-- Physical volumes --
PV Name /dev/sdb
PV UUID B0K2qH-0UF4-gphE-MLi3-RFXH-HEP9-9FMbA9
PV Status allocatable
Total PE / Free PE 2047 / 1297


Step 8 - Alternatively, you can execute the following command:

# lvcreate –L 3000 –n SecretData vg_group01

A volume created in this way will have its own name assigned by the user during creation. For previously created volumes, you can change the name as follows:

# lvrename /dev/vg_group01/lvol0 /dev/vg_group01/SecretData
Renamed “lvol0” to “SecretData” in volume group “vg_group01”

Step 9 - Check what has changed after renaming

# lvdisplay vg_group01
-- Logical volume --
LV Name /dev/vg_group01/SecretData
VG Name vg_group01
LV UUID mk9dJM-3qt7-ypbC-nsks-I8Gh-9V3d-4BNE6s
LV Write Access read/write
LV Status available
# open 0
LV Size 2.93 GiB

Current LE 750
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2

Now you know how to create logical volumes and how to name or rename them.

At this point, it is worth considering how to achieve a partition layout where you divide a previously created volume group into a selected number of parts of exactly the same size?


Step 1 - Check available partitions.

Check available partitions:


[root@RHEL01 ~]# cat /proc/partitions
major minor  #blocks  name

   8        0   20971520 sda
   8        1     512000 sda1
   8        2   20458496 sda2
   8       16    8388608 sdb
   8       17    2104483 sdb1
   8       18    6281415 sdb2
 253        0   18391040 dm-0
 253        1    2064384 dm-1