- Disable swapping for the associated logical volume:
# swapoff -v /dev/VolGroup00/LogVol01 - Reduce the LVM2 logical volume by 512 MB:
# lvm lvreduce /dev/VolGroup00/LogVol01 -L -512M - Format the new swap space:
# mkswap /dev/VolGroup00/LogVol01 - Enable the extended logical volume:
# swapon -va - Test that the logical volume has been reduced properly:
# cat /proc/swaps # free
Source : http://www.centos.org/docs/5/html/Deployment_Guide-en-US/s1-swap-removing.html
