Multiple linux sharing one common swap

[Myles Green]

On Sun, 2004-26-12 at 14:58 -0500, alex wrote:
> I thought I'd be clever to avoid duplication by having 4 linuxes (two 
> KNOPPIX, one SuSE, and one UBUNTU) share a single common swap  but now 
> I'm  wondiring if  it's a dumb idea  There are also two MS Windows and 
> four utility partitions (catch-alls for Windows and linux))
> 
> ubuntu's grub controls bootup nicely, all systems seem to work as they 
> should but something seems to have upset the original partitioning 
> arrangement.
> 
> When I partitioned for Linux, I  created a single 500 MB swap partition  
> on hdb and  four contiguous 3.5 MB  linux root partitions on hda.   Each 
> partition was cleanly defined..   I used   Ranish  Partition Manager  to 
> do this.
> 
> Installation of the four Linuxes seemed normal,  Each Linux  root ( / ) 
> was placed in its partition (hda5, hda6, hda7, and hda8 and at the same 
> time, I selected the common 500 MB swap partition (hdb6) when I 
> installed each  root..  Each linux seems to work perfectly so apparently 
> no real harm has been done..
> 
> The problem is, when I recently examined the partiioning scheme, I 
> discovered that the linux partitons are no longer contiguous,  there's a 
> gap between them, on the order of 20 MB.----there is no gap between the 
> non-linux partitions  This is observable on Ranish Partition Manager and 
> also on  a graphical partitioner.
> 
> Could it be that the common shared swap is being ignored and each Linux 
> steals some swap space from it's own root partition thus making it 
> appear that there's a space between root partitions?    What can be done 
> to make my original plan work, each Linux sharing that single 500 MB 
> swap without creating that gap between / partitions?
> 

Hi Alex,
There should be no problems as a result of sharing your swap partition,
I've done this for years on my desktop machines. Personally, I always
use the same partitioning software (linux fdisk) to avoid the 'lost
space' problem you're experiencing; it seems that mixing your
partitioning software, ie Ranish and "a graphical partitioner" (wouldn't
be Partition Magic would it?) results in these gaps appearing. If you
have a mechanism for backing up your data from the various installations
you have going there, you should do that and then wipe the disc clean
( dd if=/dev/zero of=/dev/hd? ) and make all your partitions with one
tool. I suggest doing that with your favourite Live-CD (Ubuntu?) or
floppy distro (tomsrtbt comes to mind) and either fdisk or cfdisk.
Unfortunately, sometimes the long way is actually the shortest way - or
at least the most headache-free way.

HTH,

Myles, the younger OF ;-)

> alex, the OF

-- 
Myles Green <rmg57 at telus.net> Calgary AB Canada
Ubuntu Linux 5.04 "Hoary Hedgehog" Development Branch http://www.ubuntulinux.org/
My GPG/PGP public key (9D02F338) is available on this server: http://keyserver-beta.pgp.com/
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