Check Swap Space in Linux
Linux uses Swap Space to back its physical memory with an overflow area. In most cases the suggested amount is a disk space equal to the amount of physical memory you have installed.
Below, we'll check to see how the swap is defined and being used by your system.
Contents
Steps
- From your root userid, enter the command "swapon -s". This will show your allocated swap disk or disks, if any. Your output should look like the following:
- Enter the command "free". This will show both your memory and your swap usage. Your output should be similar to the following:
- In either of the above, look for the used space, compared to the total size. If a large percentage of the swap space is used, then one of two actions may be warranted: you may want to either add an additional swap disk to increase the available swap space, or you may want to add additional physical memory to the system.
Tips
- You can also see your swap disk(s) by using the "mount" command, but it won't show the allocated or used space.
Warnings
- Adding more swap isn't always the answer. Using swap means that you're over-committed on physical memory, and swapping takes time. This takes its toll on your system's performance. If you're swapping, and having performance problems, more memory may be the real answer.
