6.4. Removing a Disk from a Logical Volume

This example shows how you can remove a disk from an existing logical volume, either to replace the disk or to use the disk as part of a different volume. In order to remove a disk, you must first move the extents on the LVM physical volume to a different disk or set of disks.

6.4.1. Moving Extents to Existing Physical Volumes

In this example, the logical volume is distributed across four physical volumes in the volume group myvg. 
# pvs -o+pv_used
  PV         VG   Fmt  Attr PSize  PFree  Used
  /dev/sda1  myvg lvm2 a-   17.15G 12.15G  5.00G
  /dev/sdb1  myvg lvm2 a-   17.15G 12.15G  5.00G
  /dev/sdc1  myvg lvm2 a-   17.15G 12.15G  5.00G
  /dev/sdd1  myvg lvm2 a-   17.15G  2.15G 15.00G
We want to move the extents off of /dev/sdb1 so that we can remove it from the volume group.
If there are enough free extents on the other physical volumes in the volume group, you can execute the pvmove command on the device you want to remove with no other options and the extents will be distributed to the other devices. 
# pvmove /dev/sdb1
  /dev/sdb1: Moved: 2.0%
 ...
  /dev/sdb1: Moved: 79.2%
 ...
  /dev/sdb1: Moved: 100.0%
After the pvmove command has finished executing, the distribution of extents is as follows: 
# pvs -o+pv_used
  PV         VG   Fmt  Attr PSize  PFree  Used
  /dev/sda1  myvg lvm2 a-   17.15G  7.15G 10.00G
  /dev/sdb1  myvg lvm2 a-   17.15G 17.15G     0
  /dev/sdc1  myvg lvm2 a-   17.15G 12.15G  5.00G
  /dev/sdd1  myvg lvm2 a-   17.15G  2.15G 15.00G
Use the vgreduce command to remove the physical volume /dev/sdb1 from the volume group. 
# vgreduce myvg /dev/sdb1
  Removed "/dev/sdb1" from volume group "myvg"
# pvs
  PV         VG   Fmt  Attr PSize  PFree
  /dev/sda1  myvg lvm2 a-   17.15G  7.15G
  /dev/sdb1       lvm2 --   17.15G 17.15G
  /dev/sdc1  myvg lvm2 a-   17.15G 12.15G
  /dev/sdd1  myvg lvm2 a-   17.15G  2.15G
The disk can now be physically removed or allocated to other users.

6.4.2. Moving Extents to a New Disk

In this example, the logical volume is distributed across three physical volumes in the volume group myvg as follows: 
# pvs -o+pv_used
  PV         VG   Fmt  Attr PSize  PFree  Used
  /dev/sda1  myvg lvm2 a-   17.15G  7.15G 10.00G
  /dev/sdb1  myvg lvm2 a-   17.15G 15.15G  2.00G
  /dev/sdc1  myvg lvm2 a-   17.15G 15.15G  2.00G
We want to move the extents of /dev/sdb1 to a new device, /dev/sdd1.

6.4.2.1. Creating the New Physical Volume

Create a new physical volume from /dev/sdd1. 
# pvcreate /dev/sdd1
  Physical volume "/dev/sdd1" successfully created

6.4.2.2. Adding the New Physical Volume to the Volume Group

Add /dev/sdd1 to the existing volume group myvg. 
# vgextend myvg /dev/sdd1
  Volume group "myvg" successfully extended
# pvs -o+pv_used
  PV         VG   Fmt  Attr PSize  PFree  Used
  /dev/sda1   myvg lvm2 a-   17.15G  7.15G 10.00G
  /dev/sdb1   myvg lvm2 a-   17.15G 15.15G  2.00G
  /dev/sdc1   myvg lvm2 a-   17.15G 15.15G  2.00G
  /dev/sdd1   myvg lvm2 a-   17.15G 17.15G     0

6.4.2.3. Moving the Data

Use the pvmove command to move the data from /dev/sdb1 to /dev/sdd1. 
# pvmove /dev/sdb1 /dev/sdd1
  /dev/sdb1: Moved: 10.0%
...
  /dev/sdb1: Moved: 79.7%
...
  /dev/sdb1: Moved: 100.0%

# pvs -o+pv_used
  PV          VG   Fmt  Attr PSize  PFree  Used
  /dev/sda1   myvg lvm2 a-   17.15G  7.15G 10.00G
  /dev/sdb1   myvg lvm2 a-   17.15G 17.15G     0
  /dev/sdc1   myvg lvm2 a-   17.15G 15.15G  2.00G
  /dev/sdd1   myvg lvm2 a-   17.15G 15.15G  2.00G

6.4.2.4. Removing the Old Physical Volume from the Volume Group

After you have moved the data off /dev/sdb1, you can remove it from the volume group. 
# vgreduce myvg /dev/sdb1
  Removed "/dev/sdb1" from volume group "myvg"
You can now reallocate the disk to another volume group or remove the disk from the system.