How to create a "fixed-space"-a folder that is EXT2 inside and whatever size-50MB?

linus72 · 04-08-2009, 07:40 AM

I know Puppy does this when it installs frugal-install and Slax/Wolvix have the Slax-save which creates a folder of varying size-but how do I do it-and make it either dynamic or fixed size?
Is this a type of Virtual HD?

GazL · 04-08-2009, 08:21 AM

If you mean a filesystem in a file, it sounds like you're talking about using loop devices.

You'd do it something like this

Code:

dd if=/dev/zero bs=4G of=/var/filesys_in_a_file.fs
losetup /dev/loop0 /var/filesys_in_a_file.fs
mke2fs /dev/loop0
mount /dev/loop0 /media/loopfilesys

The red bits you'd only do the once when you first create the filesystem. For mounting a loopback filesystem that you've already created there a '-o loop' option on the mount command to shortcut needing to use the losetup command.

Hope that helps...

PS. I don't know how you'd make it's size dynamic. Is it even possible?

linus72 · 04-08-2009, 08:33 AM

I believe it may be possible-even probable-
Puppy creates a folder that is EXT2 inside when it does a frugal install, the DSL backup.tar.gz/mydsl on your HD also expands when you add to it.
The Billix-0.18 version has a "hardisk" in the Qemu folder that is 60+MB and the virtual DSL saves settings, etc to this "hd".
Slax/Wolvix have a similar saving feature-Wolvix creates a folder of 56/+MB on your USB to save to.
Anyway-when I made my latest multidistro toolkit I included DSL, and then thought about doing this stuff-now I have a CD with the DSL backup on the CD too-problem is my f*****n! PC can't write CD-RW for some reason so I can't test it!
I do believe it can be done by putting the "save" folder on the CD-RW with the OS and using the "append" line at boot to either load the saved stuff or boot fresh.

GazL · 04-08-2009, 08:47 AM

As I understand it, most of the "live" distributions normally make use of a ramdisk/tmpfs and untar the system into that, which is not quite the same thing as i was talking about. I'm not entirely sure we're talking about the same thing here. Filesystems mounted on loop devices certainly can't grow dynamically, though with a bit of hocus-pocus you could probably resize them while they're offline. It's probably help if I knew a bit more about puppy and its 'save folders' whatever they are. I'll have to do a bit of reading.