Gentoo Archives: gentoo-user

From: Simon <turner25@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Any experience with swapfiles?
Date: Wed, 02 May 2012 21:00:35
In Reply to: [gentoo-user] Any experience with swapfiles? by walt
1 I haven't used a swap partition on any of my systems (intel celeron,
2 p3, amd64, intel xeon) for over... what... 10 years?
3 Swapfiles only, and sometimes I don't even mount the swap. Although I
4 have never removed support for any kind of swap from my kernel.
7 dd if=/dev/zero of=/path/to/swapfile bs=1M count=1024
8 mkswap /path/to/swapfile
9 swapon /path/to/swapfile
10 (btw, I like to put the swap file in /root or /boot, but that's my
11 pref, on space constrained PC, i would put a swapfile on every drive
12 to distribute it).
15 I don't have access to my box to confirm but I think /etc/fstab would
16 be setup the same as normal swap except with the file path instead of
17 the device partition.
19 Except for issue pointed out by Paul about hibernation, dd line above
20 takes care of non-sparsity. As for security, having a swap is less
21 secure than having none: a malicious persion could extract
22 information from programs memory which was swapped (ie, like the
23 decripted information "for your eyes only").
25 Having no swap at all was a problem on small systems with little RAM
26 when emerging big stuff (boost failed all the time on a pc with
27 256mb).
29 Resizing swap "on-the-fly" with swapfiles:
30 And on HDD-space constrained system, i used to have several
31 swapfiles that I created and deleted in the manner above, that I named
32 swapfile-256, swapfile-512, etc... A smooth "upgrade of swap
33 on-the-fly" was done this way: say I had 256 swapped on, I could swap
34 on a new 512 (768 total at moment, all data still on 256mb file), then
35 swapoff the 256 (takes a bit of time for swap data to move over),
36 delete the 256. Downgrade can be done in the same manner. "swapon
37 -s" (status) will be a good friend of yours now.
39 Good luck!
41 Simon
44 On Wed, May 2, 2012 at 2:53 PM, walt <w41ter@×××××.com> wrote:
45 > I have two machines with 4GB of ram and I've never seen either one use
46 > swapspace (yet) so I'm thinking I could delete my swap partitions and
47 > substitute a much smaller swapfile -- if it's safe.
48 >
49 > Any downside to using a swap file instead of a swap partition, maybe
50 > depending on which filesystem you use, or something?  Security holes?
51 > Any horror stories out there?
52 >
53 >


Subject Author
[gentoo-user] Re: Any experience with swapfiles? walt <w41ter@×××××.com>