Linux Format forums

Narendra · Posted: Wed Sep 07, 2011 9:48 am Post subject: What is swap partition?

Hello,
I have created a swap partition of 8 gb and installed ubuntu with 30 gb of space.
When the Ubuntu fills up with its all 30 gbs, will the rest of the files get swapped to this SWAP partition?
Please advise.
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Narendra

RedWillow · LXF regular Joined: Thu May 29, 2008 2:05 pm Posts: 716

No. A swap partition is analogous to the pagefile.sys file in Windows. It is used to swap stuff out of RAM if your RAM is getting too full.

Wikipedia article on paging:

http://en.wikipedia.org/wiki/Swap_partition

Dutch_Master · LXF regular Joined: Tue Mar 27, 2007 2:49 am Posts: 2354

An 8 GB swap is quite big. In general: the more RAM you have, the less likely the kernel needs swap to be used. Right now, the machines I've build have 16GB RAM, on a harddrive of just 30 GB any swap larger then 4 GB is a waste of space. In fact, using SSD's for the system make swap effectively unnecessary as these are so quick it'll have minimal impact on performance.

Narendra · Posted: Wed Sep 07, 2011 2:34 pm Post subject:

Thank you very much for your replies.

i tried deleted the swap partition but then the computer won't boot up, showed grub error!
I had backed up Home Folder, the Thunderbird and the Firefox. And I do not now how to fix up the Grub Error, So I reinstalled Ubuntu, without the swap partion. I already have 4 Gb of DDR3 Ram.
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Narendra

Ram · Posted: Wed Sep 07, 2011 3:27 pm Post subject:

DM, with only a quarter of the swap to actual memory, are you able to suspend / hibernate your system?
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Dutch_Master · LXF regular Joined: Tue Mar 27, 2007 2:49 am Posts: 2354

@RAM: I don't suspend nor hibernate any of my systems, so... Wink

However, theoretically it should be possible, as long as you close all running applications so it's only the kernel that needs room for its suspended state. In light of the above, it'll be no surprise that I haven't tried it myself Razz

nelz · Posted: Wed Sep 07, 2011 6:25 pm Post subject:

The full contents of active memory are saved, compressed if you want, but you can suspend to a file so a large swap is unnecessary.
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Rhakios · Posted: Thu Sep 08, 2011 1:15 pm Post subject:

nelz · Posted: Thu Sep 08, 2011 2:43 pm Post subject:

If you're using TuxonIce to suspend, it's a matter of changing one line in the config file. That would make for a rather short tutorial.

If you're not using TuxOnIce, you deserve what you get Smile

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Rhakios · Posted: Thu Sep 08, 2011 2:56 pm Post subject:

nelz · Posted: Thu Sep 08, 2011 3:00 pm Post subject:

It's an enhanced suspend that adds extra options, like suspending to a disk file, aborting a suspend and a couple of other goodies. I've used it for so long, I'd forgotten about the standard offering being more limited.
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Unix is user-friendly. It's just very selective about who it's friends are.

pastychomper · Joined: Wed Apr 07, 2010 11:54 am Posts: 36

Impressive. I'm assured swap files have been as fast as swap partitions for some time, so if TuxonIce is as good as it sounds then presumably there's no longer a need to have a swap partition at all.

I suppose having a dedicated partition means you can keep the swap on the fastest edge of the disc, so maybe it's still worthwhile - but would that be offset by the drive heads having to travel further from the filesystem partition(s) to do a read?

nordle · LXF regular Joined: Fri Apr 08, 2005 10:56 pm Posts: 1497

Can't be arsed to fact check.
But does Suspend not go to RAM (assuming STR in bios), so swap is not essential anyway?
Hibernate may require disk space, but STR does not.

I've got 2GB RAM and 512MB swap. Never had a problem suspending PC. Longest I think was 30 something days with a daily suspend, then kernel update forced actual reboot.
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Nuke · Posted: Wed Sep 14, 2011 1:58 pm Post subject: Two Topics Here?

Ram · Posted: Wed Sep 14, 2011 5:27 pm Post subject:

If suspend suspends to ram (power still consumed) where is hibernate stored no power used.
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Ubuntu LXDE 12.04 running on AMD Phenom II*4; ASUS Crosshair III Formula MB; 4 GB Ram.....