LVM Logical Volumes

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A logical volume is created in a volume group. Logical volumes that contain a file system can be mounted. The use of logical volumes is similar to the use of partitions and is accomplished with the same standard commands (mkfs, mount, fsck, df, ...).

The commands used to manage a logical volume start with lv:

lvchange       lvextend       lvconvert      lvm
lvcreate       lvmchange      lvdisplay      lvmconf
lvmdiskscan    lvmdump        lvmetad        lvmsadc
lvmsar         lvreduce       lvremove       lvrename
lvresize       lvs            lvscan

lvcreate

Use the lvcreate command to create Logical Volumes in a Volume Group. This example creates an 8GB Logical Volume in Volume Group vg32:

# lvcreate -L5G vg32
  Logical volume "lvol0" created

As you can see, lvm automatically names the Logical Volume lvol0. The next example creates a 200MB Logical Volume named MyLV in Volume Group vg32:

# lvcreate -L200M -nMyLV vg32
  Logical volume "MyLV" created

The next example does the same thing, but with different syntax:

# lvcreate --size 200M -n MyLV vg32
  Logical volume "MyLV" created

This example creates a Logical Volume that occupies 10 percent of the Volume Group:

# lvcreate -l 10%VG -n MyLV2 vg32
  Logical volume "MyLV2" created

This example creates a Logical Volume that occupies 30 percent of the remaining free space in the Volume Group:

# lvcreate -l 30%FREE -n MyLV3 vg32
  Logical volume "MyLV3" created

lvremove

Use the lvremove command to remove Logical Volumes from a Volume Group. Removing a Logical Volume requires the name of the Volume Group.

# lvremove vg32/MyLV
Do you really want to remove active logical volume "MyLV"? [y/n]: y
  Logical volume "MyLV" successfully removed

Removing multiple Logical Volumes will request confirmation for each individual volume.

# lvremove vg32/MyLV vg32/MyLV2 vg32/MyLV3
Do you really want to remove active logical volume "MyLV"? [y/n]: y
  Logical volume "MyLV" successfully removed
Do you really want to remove active logical volume "MyLV2"? [y/n]: y
  Logical volume "MyLV2" successfully removed
Do you really want to remove active logical volume "MyLV3"? [y/n]: y
  Logical volume "MyLV3" successfully removed

lvextend

Extending the volume is easy with lvextend. This example extends a 200MB Logical Volume with 100 MB:

# lvdisplay /dev/vg32/lvol0 | grep Size
  LV Size               200.00 MB
# lvextend -L +100 /dev/vg32/lvol0
  Extending logical volume lvol0 to 300.00 MB
  Logical volume lvol0 successfully resized
# lvdisplay /dev/vg32/lvol0 | grep Size
  LV Size               300.00 MB

The next example creates a 100MB Logical Volume, and then extends it to 500MB:

# lvcreate --size 100M -n extLV vg32
  Logical volume "extLV" created
# lvextend -L 500M vg32/extLV
  Extending logical volume extLV to 500.00 MB
  Logical volume extLV successfully resized

This example doubles the size of a Logical Volume.

# lvextend -l+100%LV vg32/extLV
  Extending logical volume extLV to 1000.00 MB
  Logical volume extLV successfully resized

lvrename

Renaming a Logical Volume is done with lvrename. This example renames extLV to bigLV in the vg32 Volume Group:

# lvrename vg32/extLV vg32/bigLV
  Renamed "extLV" to "bigLV" in volume group "vg32"

lvs

Use lvs for a quick look at all existing logical volumes. Below you can see two logical volumes named LogVol00 and LogVol01:

# lvs
  LV       VG         Attr   LSize Origin Snap% Move Log Copy%
  LogVol00 vg33       -wi-ao 14.88G
  LogVol01 vg33       -wi-ao  1.00G

lvscan

The lvscan command will scan all disks for existing Logical Volumes:

# lvscan
  ACTIVE            '/dev/vg33/LogVol00'  [14.88 GB]  inherit
  ACTIVE            '/dev/vg33/LogVol01'  [1.00 GB] inherit

lvdisplay

More detailed information about logical volumes is available through the lvdisplay command.

# lvdisplay vg33/LogVol01
  --- Logical volume ---
  LV Name               /dev/vg33/LogVol01
  VG Name               vg33
  LV UUID               RnTGK6-xWsi-t530-ksJx-7cax-co5c-A1KlDp
  LV Write Access       read/write
  LV Status             available
  # open                1
  LV Size               1.00 GB
  Current LE            32
  Segments              1
  Allocation            inherit
  Read ahead sectors    0
  Block device          253:1