Procedure to Reduce the Logical Volume

Scenario : Suppose we want to reduce /home by 2GB which is LVM and formated as ext4.

[root@cloud ~]# df -h /home/
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_cloud-LogVol00
12G  9.2G  1.9G  84% /home

Step:1 Umount the filesystem

[root@cloud ~]# umount /home/

Step:2 check the filesystem for Errors using e2fsck command.

[root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00
e2fsck 1.41.12 (17-May-2010)
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/vg_cloud-LogVol00: 12/770640 files (0.0% non-contiguous), 2446686/3084288 blocks

Note: In the above command e2fsck , we use the option ‘-f’ to forcefully check the filesystem , even if the filesystem is clean.

Step:3 Shrink the size of /home to desire size.

As shown in the above scenario , size of /home is 12 GB , so by reducing it by 2GB , then the size will become 10GB.

[root@cloud ~]# resize2fs /dev/mapper/vg_cloud-LogVol00 10G
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/vg_cloud-LogVol00 to 2621440 (4k) blocks.
The filesystem on /dev/mapper/vg_cloud-LogVol00 is now 2621440 blocks long.

 Step:4 Now reduce the size using lvreduce command.

[root@cloud ~]# lvreduce -L 10G /dev/mapper/vg_cloud-LogVol00
WARNING: Reducing active logical volume to 10.00 GiB
THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce LogVol00? [y/n]: y
Reducing logical volume LogVol00 to 10.00 GiB
Logical volume LogVol00 successfully resized

 Step:5 For the safer side , now check the reduced filesystem for errors

[root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00
e2fsck 1.41.12 (17-May-2010)
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/vg_cloud-LogVol00: 12/648960 files (0.0% non-contiguous), 2438425/2621440 blocks

Step:6 Mount the file system and verify the size.

[root@cloud ~]# mount /home/
[root@cloud ~]# df -h /home/
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_cloud-LogVol00
9.9G  9.2G  208M  98% /home