To be even safer, you could revert to run level 1 or single-user mode. This displays the current partition tables on each drive. Identify the current swap partition by number. Use the fdisk p sub-command to verify that there is enough free space on the disk to create the new swap partition.
The space on the hard drive is shown in terms of byte blocks and starting and ending cylinder numbers, so you may have to do some math to determine the available space between and at the end of allocated partitions. Use the n sub-command to create a new swap partition. By default, it chooses the lowest-numbered available cylinder. If you wish to change that, type in the number of the starting cylinder.
The fdisk command now allows you to enter the size of the partitions in a number of formats, including the last cylinder number or the size in bytes, KB or MB.
Type in M, which will give about 4GB of space on the new partition for example , and press Enter. Use the p sub-command to verify that the partition was created as you specified it.
Note that the partition will probably not be exactly what you specified unless you used the ending cylinder number. The fdisk command can only allocate disk space in increments on whole cylinders, so your partition may be a little smaller or larger than you specified.
If the partition is not what you want, you can delete it and create it again. Now it is necessary to specify that the new partition is to be a swap partition.
The sub-command t allows you to specify the type of partition. So enter t , specify the partition number, and when it asks for the hex code partition type, type 82, which is the Linux swap partition type, and press Enter.
When you are satisfied with the partition you have created, use the w sub-command to write the new partition table to the disk. The fdisk program will exit and return you to the command prompt after it completes writing the revised partition table. You will probably receive the following message as fdisk completes writing the new partition table:. At this point, you use the partprobe command to force the kernel to re-read the partition table so that it is not necessary to perform a reboot.
Now use the command fdisk -l to list the partitions and the new swap partition should be among those listed. The existing line may look like this:. Add a new line that looks similar this, depending upon the location of your new swap partition:. Be sure to use the correct partition number. Now you can perform the final step in creating the swap partition. Use the mkswap command to define the partition as a swap partition. Your new swap partition is now online along with the previously existing swap partition.
You can use the free or top commands to verify this. If your disk setup uses LVM, changing swap space will be fairly easy.
Again, this assumes that space is available in the volume group in which the current swap volume is located. By default, the installation procedures for Fedora Linux in an LVM environment create the swap partition as a logical volume. This makes it easy because you can simply increase the size of the swap volume. First, verify that swap exists and is a logical volume using the lvs command list logical volume.
You can see that the current swap size is 8GB. In this case, we want to add 2GB to this swap volume. First, stop existing swap. You may have to terminate running programs if swap space is in use. Now verify the new swap space is present with the list block devices command. Again, a reboot is not required. You can also use the swapon -s command, or top , free , or any of several other commands to verify this. Note that the different commands display or require as input the device special file in different forms.
This article was originally published in September and has been updated with additional information by the editor. It used to be that swap space was something you did need to think about with some memory-intensive processes. Nowadays, with computers have a lot of RAM, and fast processors, it's of no great concern.
You can see this by running some application that monitors your system and watch the swap usage under heavy load. It's hard to see a dent in swap. I see heavy swap usage even on systems with large amounts of RAM when doing nightly backups based on rsync. Many other times the swap usage is minimal but still present. A computer has a sufficient amount of physical memory but most of the time we need more so we swap some memory on disk.
Swap space is a space on a hard disk that is a substitute for physical memory. It is used as virtual memory which contains process memory images. Whenever our computer runs short of physical memory it uses its virtual memory and stores information in memory on disk.
It is also called a swap file. Virtual memory is a combination of RAM and disk space that running processes can use. Swap space is the portion of virtual memory that is on the hard disk, used when RAM is full.
Attention reader! Save the file! Now you should be able to hibernate and resume! Note: btrfs does not support swap files at the moment. See man swapon. See man fallocate. The swappiness parameter controls the tendency of the kernel to move processes out of physical memory and onto the swap disk. Because disks are much slower than RAM, this can lead to slower response times for system and applications if processes are too aggressively moved out of memory.
Reducing the default value of swappiness will probably improve overall performance for a typical Ubuntu desktop installation. Note : Ubuntu server installations have different performance requirements to desktop systems, and the default value of 60 is likely more suitable.
If vm. The Linux kernel assigns priorities to all swap containers. To see the priorities that the Linux Kernel assigns to all the swap containers use this command. Consult the manual page of swapon for more info man swapon Should I reinstall with more swap? Definitely not. With the 2. My swap is not being used!
Swap may not be needed Start many memory consuming applications e. Gimp, web browsers, LibreOffice etc and then issue the free command again. Is swap being used now? Is there a swap partition at all? Use this command to see all partitions sudo parted --list You should be able to see something like this in the output 5 GB GB To create a swap partition you can boot from your Ubuntu install CD, create a swap partition out of the free space on your hard disk and then interrupt your installation.
Enabling a swap partition In case you do have a swap partition, there are several ways of enabling it. This enables swap on boot.
This can hurt the multitasking performance of your desktop system. You can use the following script to get the swap manually back into RAM: Place the script e. Partners Support Community Ubuntu.
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