increasing ram, need to increase swap

phreakshew · 04-02-2007, 09:32 PM

hello all,

I'm running Ubuntu 6.06 on a Toshiba Satellite laptop with 256mb (PC133) RAM. I want to increase the RAM to 512 and I have read that it is good to make the swap twice the size of available RAM. How can I do this without reinstalling the OS? I have read similar threads but wasn't sure if those directions would work in Ubuntu so I'm asking it here.

Please and Thank You

macemoneta · 04-02-2007, 09:58 PM

Swap is swap; the distribution doesn't much matter. The easiest way to add swap is to add a second level of swap in a file. For example, to add 512MB of swap (as root):

1. Prepare the swapfile:

Code:

# dd if=/dev/zero of=/swapfile bs=1M count=512
512+0 records in
512+0 records out
536870912 bytes (537 MB) copied, 22.0228 seconds, 24.4 MB/s

2. Format it as swap:

Code:

# mkswap /swapfile
Setting up swapspace version 1, size = 536866 kB

3. Add it to /etc/fstab:

Code:

/swapfile   swap   swap   defaults   0 0

4. Start using it (will happen automatically at boot in the future):

Code:

# swapon /swapfile

You can verify it's now available with:

Code:

# swapon -s
Filename                                Type            Size    Used    Priority
/dev/hda3                               partition       2032212 1648    -1
/swapfile                               file            524280  0       -2

phreakshew · 04-02-2007, 11:44 PM

Thanx! That was very helpful! So, with this setup, if the computer uses up one swap partition it will then automatically dip into the next swap? How much swap do YOU recommend?

macemoneta · 04-02-2007, 11:59 PM

Yes, when the primary (partition) is full, it will use the swapfile. This is actually more efficient than a single large area, as it keep seeks short.

There's no "one size fits all" with swap. As your real memory increases, you actually need less. I'd recommend 4x real at 128MB, but decreasing to 1/4 real (256MB) at 1GB. Your usage pattern may be different, but I typically have a dozen or more windows/applications running, and that's fine for me.

That's another nice thing about using a swapfile; you can estimate low and add it if necessary on the fly. You may want to run for a while without increasing your swap after increasing your RAM, and see what your usage is. If you don't need it, don't add it.

phreakshew · 04-03-2007, 12:15 AM

one last thing- how do I check to see how much / how often swap is accessed?

thanks again for your help!

macemoneta · 04-03-2007, 12:30 AM

The 'swapon -s' will give you a current snapshot. The 'top' command will also provide the swap usage in the header. You can also run one of the many system monitors, like gkrellm, conky, etc. They can display swapping information in near-realtime if you want to keep an eye on it.

If you don't want to install anything Gnome comes with a monitor for the panel... Right-click on an empty area on your panel (usually at the top/bottom of the screen), and select 'Add to Panel'. Scroll down to the 'System Monitor' and click on Add, then close. The monitor will be added to the panel. You can right click on it and select 'Preferences' to add a monitor for swap.

phreakshew · 04-03-2007, 12:48 AM

that's great! I've actually been using system monitor but never right clicked on it! Still a

shipon_97 · 12-26-2016, 11:23 PM

i have a question .

From where this /swapfile takes 512M space ? is it take space from available RAM or from Local HDD ?

astrogeek · 12-26-2016, 11:49 PM

You have replied to a thread which has been inactive for almost ten years.

You are encouraged to open your own thread with a complete description of your problem so that your question will receive better exposure and attract more relevant answers.

Swap is always allocated on a storage device such as a HDD or SSD, either as a partition or a file. It is used to temporarily free blocks of used but inactive RAM for use by higher priority processes.

You may find this page helpful, ArchWiki: Swap.