4.4.10. Shrinking Logical Volumes

To reduce the size of a logical volume, first unmount the file system. You can then use the lvreduce command to shrink the volume. After shrinking the volume, remount the file system.

Warning

It is important to reduce the size of the file system or whatever is residing in the volume before shrinking the volume itself, otherwise you risk losing data.
Shrinking a logical volume frees some of the volume group to be allocated to other logical volumes in the volume group.
The following example reduces the size of logical volume lvol1 in volume group vg00 by 3 logical extents. 
lvreduce -l -3 vg00/lvol1