Extending a LVM in a Virtual Machine Running on Red Hat or Cent OS

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In this article provides steps for extending the root partition residing in a logical volume created with Logical Volume Manager (LVM) in a virtual machine running Red Hat/Cent OS.


To extend the logical volume:

Note: These steps only apply to EXT3 file systems.

Caution: VMware recommends to take a complete backup of the virtual machine prior to making these changes.

  1. Power off the virtual machine.
  2. Edit the virtual machine settings and extend the virtual disk size.
  3. Power on the virtual machine.
  4. Identify the device name, which is by default /dev/sda, and confirm the new size by running the command:
    # fdisk -l
  5. Create a new primary partition:
    1. Run the command:# fdisk /dev/sda (depending the results of the step 4)
    2. Press p to print the partition table to identify the number of partitions. By default, there are 2: sda1 and sda2.
    3. Press n to create a new primary partition.
    4. Press p for primary.
    5. Press 3 for the partition number, depending on the output of the partition table print.
    6. Press Enter two times.
    7. Press t to change the system’s partition ID.
    8. Press 3 to select the newly creation partition.
    9. Type 8e to change the Hex Code of the partition for Linux LVM.
    10. Press w to write the changes to the partition table.
  6. Restart the virtual machine.
  7. Run this command to verify that the changes were saved to the partition table and that the new partition has an 8e type:
    # fdisk -l
  8. Run this command to convert the new partition to a physical volume:Note: The number for the sda can change depending on system setup. Use the sda number that was created in step 5.
    # pvcreate /dev/sda3
  9. Run this command to extend the physical volume:
    # vgextend VolGroup00 /dev/sda3


    Note:
    To determine which volume group to extend, use the command vgdisplay.

  10. Run this command to verify how many physical extents are available to the Volume Group:# vgdisplay VolGroup00 | grep “Free”
  11. Run the following command to extend the Logical Volume:
    # lvextend -L+#G /dev/VolGroup00/LogVol00Where 

    Where # is the number of Free space in GB available as per the previous command. Use the full number output from Step 10 including any decimals.

    Note: To determine which logical volume to extend, use the command lvdisplay.

  12. Run the following command to expand the ext3 filesystem online, inside of the Logical Volume:
    # ext2online /dev/VolGroup00/LogVol00

    Notes:
    – Use resize2fs instead of ext2online for non-Red Hat virtual machines.
    – Use xfs_growfs for Red Hat, CentOS 7 and other VM Guest OS types that use the XFS file system.

  13. Run the following command to verify that the / filesystem has the new space available:
# df -h /

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