SWAP Configuration in Linux

Features:
  1. Generates additional virtual memory
  2. Temporary fix for RAM-Shortage. Permanent fix is to add more RAM.
  3. Requires no system downtime.
  4. Works with dedicated partitions.
  5. Works with existing file systems.
  6. Works accross disks, consequently improving performance.

Tasks:
  1. Define swap partition and provision
    a. 'fdisk /dev/sdb'
      ( Define a new partition and change the partition to 82 i.e., Linux swap )
    b. 'mkswap /dev/sdb2' ( The newly created partition )
    Note: If necessary reboot the system after using fdisk or parted.
    c. Add a new entry in /etc/fstab for the new swap file.
    d. 'swapon -s' displays all current swap devices.
    e. 'swapon -a' turns all the listed swap devices.
    f. 'swapon -v /dev/sdb3' Verbosely turns on the swap device.
    g. 'swapoff /dev/sdb3' disables the swap device.

  2. Define swap storage on existing file system.
    a. 'dd if=/dev/zero of=/swapfile1G bs=1024 count=1048576' (1024x1024=1048576) Creates 1G file That we can overlay a swap file system on of size : 1G
    b. 'mkswap /swapfile1G'
    c. 'swapon -v /swapfile1G'
    d. Add an entry in the /etc/fstab for permanent mounting
    e. 'swapon -a'