Red Hat System Administration II

Check for Space in the Volume Group

Use vgdisplay to check if the VG has sufficient free space to extend the LV to a total size of 700MiB.

[root@serverX ~]# vgdisplay shazam
  --- Volume group ---
  VG Name               shazam
  System ID             
  Format                lvm2
...
  VG Size               504.00 MiB
  PE Size               4.00 MiB
  Total PE              126
  Alloc PE / Size       100 / 400.00 MiB
  Free  PE / Size       26 / 104.00 MiB
  VG UUID               OBBAtU-2nBS-4SW1-khmF-yJzi-z7bD-DpCrAV

There is only 104MiB available (26 PEs x 4MiB extents) and we need at least 300MiB to have 700MiB in total. We need to extend the VG.

For later comparison, use df to check current disk free space:

[root@serverX ~]# df -h /storage
Filesystem                  Size  Used Avail Use% Mounted on
/dev/mapper/shazam-storage  397M   21M  377M   6% /storage

Create the Physical Resources

Use fdisk to create an additional partition of 512MiB and set it to type Linux LVM.

1. [root@serverX ~]# fdisk /dev/vdb

   Note: The following steps omit some output.

2. Add a new primary partition of 512MiB.

   Command (m for help): n
   Partition type:
      p   primary (2 primary, 0 extended, 2 free)
      e   extended
   Select (default p): Enter
   Using default response p
   Partition number (3,4, default 3): Enter
   First sector (1050624-20971519, default 1050624): Enter
   Using default value 1050624
   Last sector, +sectors or +size{K,M,G} (1050624-20971519, default 20971519): +512M
   Partition 3 of type Linux and of size 512 MiB is set

3. Change the partition type to Linux LVM - 0x8e.

   Command (m for help): t
   Partition number (1-3, default 3): Enter
   Hex code (type L to list all codes): 8e
   Changed type of partition 'Linux' to 'Linux LVM'

4. Write the changes to the partition table and quit.

   Command (m for help): w
   The partition table has been altered!

5. Use partprobe to register the new partitions with the kernel.

   [root@serverX ~]# partprobe

Create the Physical Volume

Use pvcreate to add the new partition as a PV.

[root@serverX ~]# pvcreate /dev/vdb3
  Physical volume "/dev/vdb3" successfully created

Extend the Volume Group

1. Use vgextend to extend the VG named shazam, using the new /dev/vdb3 PV.

   [root@serverX ~]# vgextend shazam /dev/vdb3
     Volume group "shazam" successfully extended

2. Use vgdisplay to check the shazam VG free space again. There should be plenty of free space now.

   [root@serverX ~]# vgdisplay shazam
     --- Volume group ---
     VG Name               shazam
     System ID             
     Format                lvm2
   ...
     VG Size               1012.00 MiB
     PE Size               4.00 MiB
     Total PE              253
     Alloc PE / Size       100 / 400.00 MiB
     Free  PE / Size       153 / 612.00 MiB
     VG UUID               OBBAtU-2nBS-4SW1-khmF-yJzi-z7bD-DpCrAV

   There is now 612MiB available (153 PEs x 4MiB extents); perfect.

Extend the Logical Volume

Use lvextend to extend the existing LV to 700MiB.

[root@serverX ~]# lvextend -L 700M /dev/shazam/storage
  Extending logical volume storage to 700.00 MiB
  Logical volume storage successfully resized

Resize the File System

Use xfs_growfs to extend the XFS file system to the remainder of the free space on the LV.

[root@serverX ~]# xfs_growfs /storage
meta-data=/dev/mapper/shazamstorage  isize=256    agcount=4, agsize=25600 blks
...

Verify Content Availability and New File System Size

Use df and ls | wc to review the new file system size and verify the existing files are still present.

[root@serverX ~]# df -h /storage
Filesystem                  Size  Used Avail Use% Mounted on
/dev/mapper/shazam-storage  697M   21M  677M   3% /storage
[root@serverX ~]# ls /storage | wc -l
47

The files are still there and the file system is about the size we expect.