Sometimes it can be prudent to reduce swap space after installation. For example, say you downgraded the amount of RAM in your system from 1 GB to 512 MB, but there is 2 GB of swap space still assigned. It might be advantageous to reduce the amount of swap space to 1 GB, since the larger 2 GB could be wasting disk space.
You have three options: remove an entire LVM2 logical volume used for swap, remove a swap file, or reduce swap space on an existing LVM2 logical volume.
15.2.1. Reducing Swap on an LVM2 Logical Volume
To reduce an LVM2 swap logical volume (assuming
/dev/VolGroup00/LogVol01 is the volume you want to reduce):
Procedure 15.3. Reducing an LVM2 swap logical volume
Disable swapping for the associated logical volume:
swapoff -v /dev/VolGroup00/LogVol01
Reduce the LVM2 logical volume by 512 MB:
lvreduce /dev/VolGroup00/LogVol01 -L -512M
Format the new swap space:
Enable the extended logical volume:
swapon -v /dev/VolGroup00/LogVol01
To test if the swap's logical volume size was successfully reduced, use
cat /proc/swaps or
free to inspect the swap space.