If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space.
Swap space is a portion of a hard disk drive (HDD) that is used for virtual memory. It can be whole disk partition or just a file inside an existing partition or a combination of swap partitions and swap files.
We will see how to manage SWAP Partitions on RHEL 6.x or CentOS 6.x
Steps:
1. Show current SWAP allocation
free -m
swapon -s
2. Create additional SWAP space from new partition
Reboot is required at this step
3. Make swap
mkswap /dev/sdb2
UUID=8bced662-e967-4861-9bac-6df8957b3eb5
4. Update /etc/fstab
UUID=8bced662-e967-4861-9bac-6df8957b3eb5 swap swap defaults 0 0
5. Re-reads /etc/fstab for swap
swapon -a
6. Show swap usage summary by device
swapon -s
free -m
Hope you found it informative and useful. Any questions or comments are welcomed.