Q. I am setting up Arch Linux on my laptop and I was wondering how big my swap partition should be and what file system format it should be in? (I think ext2 but I’m not sure). I have 4 gigs of ram. Thanks.

A. The key question is how much? Older versions of Unix-type operating systems (such as Sun OS and Ultrix) demanded a swap space of two to three times that of physical memory. Modern implementations (such as Linux) don’t require that much, but they can use it if you configure it. A rule of thumb is as follows: 1) for a desktop system, use a swap space of double system memory, as it will allow you to run a large number of applications (many of which may will be idle and easily swapped), making more RAM available for the active applications; 2) for a server, have a smaller amount of swap available (say half of physical memory) so that you have some flexibility for swapping when needed, but monitor the amount of swap space used and upgrade your RAM if necessary; 3) for older desktop machines (with say only 128MB), use as much swap space as you can spare, even up to 1GB.

The Linux 2.6 kernel added a new kernel parameter called swappiness to let administrators tweak the way Linux swaps. It is a number from 0 to 100. In essence, higher values lead to more pages being swapped, and lower values lead to more applications being kept in memory, even if they are idle. Kernel maintainer Andrew Morton has said that he runs his desktop machines with a swappiness of 100, stating that "My point is that decreasing the tendency of the kernel to swap stuff out is wrong. You really don’t want hundreds of megabytes of BloatyApp’s untouched memory floating about in the machine. Get it out on the disk, use the memory for something useful."

One downside to Morton’s idea is that if memory is swapped out too quickly then application response time drops, because when the application’s window is clicked the system has to swap the application back into memory, which will make it feel slow.

The default value for swappiness is 60. You can alter it temporarily (until you next reboot) by typing as root:

echo 50 > /proc/sys/vm/swappiness

If you want to alter it permanently then you need to change the vm.swappiness parameter in the /etc/sysctl.conf file.

How do I make the swap partition in linux Larger?

Q. How do I resize the linux swap partition in fedora core 5? I would like to do this from x and non-destructivly.

A. It might be easier to reinstall FC5 with the swap size you want.

How to auto-mount linux-swap, ubuntu 9.04?

Q. Hey I installed ubuntu 9.04 but it wont mount the linux-swap partition, I have to manualy "swapon" it after every startup using Gparted. How to solve this??

A. Edit
/etc/fstab

Is the entry for swap correct?