Reduce size of ext3/ext4 LVM partition in RHEL & CentOS

Scenario : Suppose we want to reduce /opt to 2GB which is LVM and formated as ext4. XFS filesystem type cannot be shrinked.

[root@rhlab01 /]# df -h
Filesystem                            Size  Used Avail Use% Mounted on
/dev/mapper/centos_rhlab01-opt   3,5G   11M  3,2G   1% /opt

[root@rhlab01 /]# lvs | grep opt
  WARNING: Not using lvmetad with older version.
  LV   VG                 Attr       LSize Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert                                
  opt  centos_rhlab01 -wi-ao---- 3,50g 

[root@rhlab01 /]# umount /opt

[root@rhlab01 /]# e2fsck -f /dev/mapper/centos_rhlab01-opt 
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/mapper/centos_rhlab01-opt: 12/229376 files (0.0% non-contiguous), 34375/916480 blocks

As shown in the above scenario , size of /opt is 3,5 GB , so by reducing it by 1,5 GB , then the size will become 2 GB.

[root@rhlab01 /]# resize2fs /dev/mapper/centos_rhlab01-opt 2g 
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/mapper/centos_rhlab01-opt to 524288 (4k) blocks.
The filesystem on /dev/mapper/centos_rhlab01-opt is now 524288 blocks long.

[root@rhlab01 /]# lvreduce -L 2g /dev/mapper/centos_rhlab01-opt
  WARNING: Not using lvmetad with older version.
  WARNING: Reducing active logical volume to 2,00 GiB.
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce centos_rhlab01/opt? [y/n]: y
  Size of logical volume centos_rhlab01/opt changed from 3,50 GiB (895 extents) to 2,00 GiB (512 extents).
  Logical volume centos_rhlab01/opt successfully resized.

[root@rhlab01 /]# e2fsck -f /dev/mapper/centos_rhlab01-opt 
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/mapper/centos_rhlab01-opt: 12/131072 files (0.0% non-contiguous), 27309/524288 blocks

[root@rhlab01 /]# mount /opt
[root@rhlab01 /]# df -h /opt
Filesystem                            Size  Used Avail Use% Mounted on
/dev/mapper/centos_rhlab01-opt   2,0G   11M  1,8G   1% /opt

Reduce size of ext3/ext4 LVM partition in RHEL & CentOS

Scenario : Suppose we want to extend / to +1000MB which is LVM and formated as ext4.

[root@rhlab01 /]# df -h /
Filesystem                            Size  Used Avail Use% Mounted on
/dev/mapper/centos_rhlab01-root  3,9G  3,8G     0 100% /

[root@rhlab01 /]# lvextend -L +1000M /dev/mapper/centos_rhlab01-root
  WARNING: Not using lvmetad with older version.
  Size of logical volume centos_rhlab01/root changed from 4,00 GiB (1024 extents) to 4,98 GiB (1274 extents).
  Logical volume centos_rhlab01/root successfully resized.

[root@rhlab01 /]# resize2fs /dev/mapper/centos_rhlab01-root
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/mapper/centos_rhlab01-root is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/mapper/centos_rhlab01-root is now 1304576 blocks long.

[root@rhlab01 /]# df -h /
Filesystem                            Size  Used Avail Use% Mounted on
/dev/mapper/centos_rhlab01-root  4,8G  3,8G  742M  84% /