UNIX for Dummies Questions & Answers

Hi All,

I have just installed my first Linux server ( Ubuntu 11.10 ).
I am sure I didn't allocate /swap , and double check by 'df -h', yes really no /swap

but when I use 'free -m' , returned a "Swap" line as below.

Code:

     total       used       free     shared    buffers     cached
Mem:          3994       3768        225          0         65       3218
-/+ buffers/cache:        484       3510
Swap:          959          0        959

Where does this memory allocation come from? How can I remove it to free up the 959MB ? In what circumstances, this allocation will be used ?

Maybe this will help:
https://help.ubuntu.com/community/SwapFaq

To look for your swap partition

Code:

grep swap /etc/fstab

Let me start with a question: Why are you so concerned about 1GB of space? ... Or: why are you so opposed to swap? I think you should read the link dude2cool posted. It looks like it's a good page of info.

In short: You can get rid of the swap space you have, and use it for something else, but it might be a lot of work.

You can get more information on the kernel's currently activated swap space with swapon -s (which simply shows you the content of /proc/swaps). Make note whether the output says something like "/dev/mapper/vg_apriori-lv_swap" or something like "/dev/sda6" -- you'll need this info later. Look at the man page for swapon/swapoff before using them for anything other than -s, but basically.. you could do a swapoff -a to turn off all registered swaps and then remove the appropriate [swap] entry from /etc/fstab, which would then allow you to reclaim that space.

In order to so, you'll either have to delete the swap logical volume (if your swap was on something that started with "/dev/mapper/...") and then extend your root (or home) logical volume ... OR, if you're really unlucky, you'll have to delete the swap partition and boot into something like PartedMagic in order to rearrange your partitions to make use of the freed up space.

Basically, I am not opposed to swap. I just thought there are 4G physical memory that the probability of running out of memory approaches zero. After reading the SwapFaq which justifies the swap space with the "Unforeseeable Circumstances", I am happy with it.