Linux Swap Partition

Hi ,

After reading a few things about how to make partitions for Linux, since I'm decided to leave Windows, I want to discuss with you about the Swap partition.

I think that all the Linux distros put the Swap partition next to the Root partition, but for example Mrkvonic, on his website, prefer to put it first.

Today the systems doesn't need a lot virtual memory because we already have and a lot of available memory. Another thing is the fact that is faster to have it +/- on the 1/3 of the disk (from the outer tracks) because the disk can do quicker movements to read all the data on it, instead of having to go every time to the outer track of the disk.
This way we will have the system files on the faster part of the disk.
On Windows this is the same...

So, I prefer the default of Linux distros and put the Swap partition next to the Root partition.

Another thing is it size. Like I already said, we don't need a lot of swapping like we needed before, so 512MB or 1GB will be more than sufficient...

What do you think?

Regards

 

I think, welcome aboard. Choose your distro wisely.

 

You probably know more than i. But Debian's wiki mentions:

http://wiki.debian.org/Swap?highlight=(swap)

I believe Alphalutra1 said the same before. I think GNU/Linux does a good job keeping unneeded memory in SWAP. It would take real knowledge for me to provide a decent answer sorry

 

It depends of what programs we use...

If we use a lot of programs at the same time, that consumes a lot of memmory, than would be nice to increase the size of the swap partition...

But it's logic that if we increase the memory on our systems we will also reduce the usage of the swap, and that is why the system became much faster...

For example, if we have 2GB of memory, it is wise to define the swap for 4GB (2 x Memory)? For what? I really doubt that we will use all that swap...

 

I'm reading similar opinions. Got this link from the Debian's forum: Understanding memory usage on Linux.

 

Nice article

Do you know if exists some similar program of Process Explorer, to Linux?

 

Built in
The Task Manager equivalent is very good. I don't know if it varies from distro to distro, they're probably all good.

 

Excellent!

I have no doubt that this time I really will change and stay with Linux...

 

I have a laptop with 256k of memory. Running either kde or gnome, my swap, and therefore my hdd, gets hammered with only a few programmes running. However, using xfce or fluxbox desktops, combined with a distro that runs few services, tends make life for my laptop far less stressful. Running Dreamlinux at the moment and find that it runs very smoothly on my machine and only uses a small portion of swap. Fluxbuntu and Elive are two others that have worked well on my machine. Strangely, Mandriva 2008, even when running xfce, still needed a lot of swap. Too many services I suspect, but I didn't know which ones I could turn off - still being a relative newbie at linux.

 

My pc with 256MB of RAM rarely touches the swap thank goodness, otherwise it slows to a crawl because my hard disk is so slow

I can't find the post I wrote on swap, but I'll quote the OpenBSD FAQ which is a pretty good source of knowledge and can put it much better then I could ever word it:

I would put around 512MB of RAM of swap, and if you ever need more, either add another partition, expand the partition, or just swap to a file, all of which are easily feasible. If my setup never swaps with only 256MB of memory, you should be just fine, but then again I like to run light, but I have been known to have firefox and java going at the same time

Cheers,

Alphalutra1

 

Hey VC, good to see you using Linux..

I have an older PC with 512mb ram and have always used around 750mb to 1 gig for swap, however, it rarely gets used, usually just a few mb at most. Probably because I don't ever really tax the system much, just do browsing and email and music, p2p, the usual. Right now I am dual booting XP and SuSE 10.3, I put SuSE on a small 8 gig partition, and it defaulted with 750mb swap, which is more than enough for me I think.. I think if you have plenty of ram, there isn't much need for much swap as it's never going to be used anyway... just wasted disk space..

 

Thanks for your opinions...

 

My bad, i did a search and didn't find anything either. You actually said in the OpenBSD thread 256 MB.
Time for reading and not posting.

 

i have these values in my /etc/sysctl.conf to make linux run faster -
vm.swappiness=20
vm.vfs_cache_pressure=50

you can read about them here http://rudd-o.com/archives/2007/10/...and-why-linux-feels-slow-and-how-to-fix-that/

more here -
http://ubuntuforums.org/showpost.php?p=1255511&postcount=43

 

Interesting tidbit. It does seems Logical that the turnings per micro/nano-second or whatever the actual rate of speed, would indeed be preminum at the spindle or center point of disc. For some odd reason, some including myself had in the past been under the false perception that the space at that area of the disk was too limited in scope to make any real difference, but then data space naturally increases as files are added beyond it.

Just trying to pin down this more acceptable placement of data.

It makes perfect sense then when looking at the physical geometry, after all it is also a mechanical device as well as electronic.

Thanks for that info.

It's been all too easy for some of us like myself content to keep Linux on the backburner while we're so consumed daily (yearly ) with securing Windows always looking for that perfect combo which seems an endless task, but finally getting somewhat better.

Linux though finally has my attention now thanks to the latest Topic and postings concerning Suse 10.3 and hope to make the most of a go with it.

 

Hi VC,

Building on comment's made by Alphalutra and yourself, these to help broaden your understanding.

Swap Partitions - http://tldp.org/HOWTO/Partition/requirements.html#SwapSize

Swap FAQ - https://help.ubuntu.com/community/SwapFaq

*Iceni's 'good to know' tip I've come across on IBM's "developerwork's."


Steve

 

Hello,

Regarding the position / size of the swap file...

1. It is or was recommended to use double the RAM size. I must admit that I have sinned and used less than that, only equivalent of RAM size, but in both cases the machines have 2GB RAM, so the memory usage is not really an issue. Even when I run VM and give them quite a lot of RAM, I have never run out of memory.

2. Position; if you have a plenty of RAM, the chances you won't need it that much ... which means that your root (and possibly home) will be on the faster tracks ... but this is not something that should bother you. You will probably never be able to tell the difference unless you are at the low end of HW.

3. Another reason why I like to position them in this order is the grow/shrink need in possible future. If your root gets crammed, but the home partition is free, you'll be able to repartition and "squeeze" outwards, but not if the swap is in the middle.

4. All of the above means nothing with good, modern PC.

Cheers,
Mrk

 

i don't think those settings are too great, i've been trying out different values for the last few days and right now it looks like no buffers are being held in RAM and the cache is very small, i think it's the vm.vfs_cache_pressure that did that, so i'm going to reboot now and delete the vm.vfs_cache_pressure=50 setting and only use vm.swappiness=20. just about all the articles i've read mention tyring the vm.swappiness setting, but not many mention vm.vfs_cache_pressure.

 

iceni60,

Thanks for the tips

Thanks for the links

That is a nice thing to use the Swap partition at the beginning, but I still prefer to use after the Root partition, because I normally choose a good size for system partition, and I think that changing the partitions sizes isn't a big problem today...

 

Just to add that this is one of the best sites for info. With time, there's much to learn here.