how to increase the swap size

[karthik2fun]

Hi,

I would like to increase the swap size on my system. I am using fedora core 8 and i have 512 mb swap . I would like to increase that to 2 gb. Kindly help me.

[ppesci]

If you want to increase the swap size without repartition the drive, you can use mkswap command. You can use an space locate in a file as a swap space. See the command with:

man mkswap

for details.

HTH

[ivancat]

create another swap partition, add it to fstab then use

su -
swapon -a

to enable all of swaps

[Hlingler]

Hello:

That whole 'mkswap' and 'swapon' feature is very nice, and very easy to use.

One question, which the manual pages don't answer: I can't "create" another partition, so I just went through the steps to create a swap file to use instead. Everything went fine, except I got one warning: "permissions unsafe - 0666 recommend 0600". I saw that normal swap is: 0660, so that's what I made the swapfile. Also changed: chown root:disk just like normal swap. Is all that OK? Any special reason it should be: 0600?

Thanx,
V

[ivancat]

well, as the owner is root there is not much difference between 0600 and 0660 as root's group members are root itself and system commands/services like halt, shutdown, sync. but for increased security 0600 may be used granting read/write permissions to root exclusively

[Hlingler]

Ah, yes right - I see. OK, thanx ivancat.

V

[bee]

i don't think that swap on a file is a good idea, it's like in windows.
As ext3, not always rewrite on the same space, maybe it'll increase the fragmentation of files and slow down the partition within that swap file is located.
???

anyhow not sure if it's real.

[Hlingler]

Hm, well, I don't pretend to know much about this at all, but the mkswap man page made one thing fairly clear:

To setup a swap file, it is necessary to create that file before initializing it with mkswap , e.g. using a command like

# dd if=/dev/zero of=swapfile bs=1024 count=65536

Note that a swap file must not contain any holes (so, using cp(1) to create the file is not acceptable).

At the very least, it gives a very pleasant illusion of increased swap space.

V