[solved] Size of swap partition

[Debug_This]

I don't know if this really matters, but I've noticed a little discrepency in the size of the swap partition in Chapter 4 of the Gentoo Handbook. The actual install guide says make it 512MB, but some of the examples it gives have different sizes. Should I just go with the suggested 512MB?

Also, on a side note, I'm not really clear on what this partition is for. I understand /boot is for booting the OS and / is the root directory of the whole operating system, but what is swap for? The only thing I can think of is like a Temp directory, but I'm not sure.

[markkuk]

Swap partition is used for the virtual menory backing store. 512MB is OK for normal desktop use, for things like image processing you may need more.

[Debug_This]

Ahh, so it's like the pagefile in Windows.

I will proceed with the install, making my swap 512MB as suggested (it's usually only really used when RAM is used up right?)

[lenkki]

The swapfile is the same as the pagefile in windows. If I'm not misstaken a general rule of thumb is to make it twice the size of your main memory. Allthough I don't know why they say so, and imo the more memory you have the less swap you should need...

Myself I have 1gb of system memory and 256mb swap, and due to a few factors I didn't foresee with my multiboot disk partitioning I also have a 8gb empty partition that I use as swap some times when I need it ( I do some developing and sometimes need to process images that are 1gb in size on disk, so it's nice )

But anyhow if you wanna be safe make the swap partition twice the size of your system memory.

My gentoo + gnome system hardly uses 200mb of memory at any normal usage so I hardly ever use the swapspace really. (excluding games and some other heavy tasks that normal users probably won't be doing

[Debug_This]

[Joseph_sys]

The general rule is to make swap partition 2 x your RAM.

Here is also an interesting article how increase swap partition if you make it too small by mistake (like I did).
http://enterprise.linux.com/enterprise/05/03/02/2250257.shtml?tid=129&tid=42

I have AMD64 with 1GB of RAM and I only created 1GB swap partition. I experienced some strange hang-ups (total freeze) during some memory intensive work. So I'm not sure if this could be attributed to a small swap space on not but I decided to double it.

I had a hard time to find any clear and relatively secure instruction on how to modify (resize) the partition to increase the swap space without putting the system at risk. But I run onto this article that describes how to "Increase your available swap space with a swap file" which seems very secure and that is what I've done.

[Debug_This]

That might also have to do with the fact that you were running a 64-bit processor. Since they can handle double the amount of memory (physical+virtual), I doubt the 2x rule applies when your talking 8 gigs as oppossed to 4. I appreciate the info though!

[Joseph_sys]

[broken_chaos]

Personal experience, I don't even need a swap partition with a gig of RAM. I've seen maybe half of it used at once (although I hardly do memory intensive things). Even on another box with 768 megs, I find a swap partition a waste personally. But that's just me.

Overall, for a 512 machine, I'd suggest at least a 512 swap partition. You could go for a gig if you wanted as well.

[Debug_This]

Thanks for clearing that up joseph, and thanks for the suggestion chaos. I am going with the 1 gig swap partition just to be safe (with a 120GB HDD I'd rather dedicate more space than I need to swap than less -- although joseph, that was a very useful article and it linked me to another good one on LVM).

OT: While checking some info on 64-bit processors at Wikipedia, I stumbled across a mention of Gentoo in this article:

[Keruskerfuerst]

swap size should be >3/2 of RAM size, if you use suspend to disk. In this case, the swap partition is used for saving the RAM.