CentOS 5 Administration - 5.3. Removing Swap Space

5.3. Removing Swap Space

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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.

5.3.1. Reducing Swap on an LVM2 Logical Volume

To reduce an LVM2 swap logical volume (assuming /dev/VolGroup00/LogVol01 is the volume you want to extend):

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
```

5.3.2. Removing an LVM2 Logical Volume for Swap

The swap logical volume cannot be in use (no system locks or processes on the volume). The easiest way to achieve this it to boot your system in rescue mode. Refer to for instructions on booting into rescue mode. When prompted to mount the file system, select Skip.

To remove a swap volume group (assuming /dev/VolGroup00/LogVol02 is the swap volume you want to remove):

Disable swapping for the associated logical volume:
```
# swapoff -v /dev/VolGroup00/LogVol02
```
Remove the LVM2 logical volume of size 512 MB:
```
# lvm lvremove /dev/VolGroup00/LogVol02
```

Remove the following entry from the /etc/fstab file:

/dev/VolGroup00/LogVol02   swap     swap    defaults     0 0

Test that the logical volume has been extended properly:
```
# cat /proc/swaps # free
```

5.3.3. Removing a Swap File

To remove a swap file:

At a shell prompt as root, execute the following command to disable the swap file (where /swapfile is the swap file):
```
# swapoff -v /swapfile
```
Remove its entry from the /etc/fstab file.
Remove the actual file:
```
# rm /swapfile
```