The swap partition is used by OS to store RAM that is not being used at the moment to make room for more RAM.
Should be as large as your RAM more or less, or twice it.
Can be shared by multiple OS, since only one OS can run at a time.
util-linux package.
Make swap partition on a file in local filesystem:
sudo dd if=/dev/zero of=/swapfile bs=1024 count=1024k
sudo mkswap /swapfile
sudo swapon /swapfile
For that to work every time:
sudo bash -c 'echo "/swapfile none swap sw 0 0" >> /etc/fstab'
Turn swap on on partition /dev/sda7:
sudo swapon /dev/sda7
Find the currently used swap partition:
swapon -s
Disable swapping:
sudo swapoff
Make a swap partition on partition with random UUID.
sudo mkswap -U random /dev/sda7
Swap must be off.