8. swap

In our previous example, I showed you how to see your partition table, let's revisit that example, more specifically this line:

Number  Start   End     Size    Type      File system     Flags

 5      6861MB  7380MB  519MB   logical   linux-swap(v1)

What is this swap partition? Well swap is what we used to allocate virtual memory to our system. If you are low on memory, the system uses this partition to "swap" pieces of memory of idle processes to the disk, so you're not bogged for memory.

Using a partition for swap space

Let's say we wanted to set our partition of /dev/sdb2 to be used for swap space.

1. First make sure we don't have anything on the partition


2. Run: mkswap /dev/sdb2 to initialize swap areas


3. Run: swapon /dev/sdb2 this will enable the swap device


4. If you want the swap partition to persist on bootup, you need to add an entry to the /etc/fstab file. sw is the filesystem type that you'll use.


5. To remove swap: swapoff /dev/sdb2

Generally you should allocate about twice as much swap space as you have memory. But modern systems today are usually pretty powerful enough and have enough RAM as it is.