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Linux question - mount fs in Windows?

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Jimdoria:
Hi everyone (especially the Linux gurus out there...)

I'm a rank noob when it comes to Linux, but I've been experimenting with QEMU-Puppy on a USB stick, and so far I like it very much.

Puppy Linux runs from RAM, and when you are done and shut it down, it saves it's changes back into a file system on the media from which it was run (thumb drive in my case.) This file system appears on the disk as pup_save.fs3 under Windows.

I'd like to get access to what's inside that file from within Windows so I can open and save things there. I found and installed Ext2 IFS which lets you mount Linux Ext2/Ext3 file systems in Windows, and gives you read/write access. (I'm guessing that because the file is named .fs3 that Puppy is using an Ext3 file system?)

The problem is that Ext2 IFS seems geared to partition based file systems. The GUI will let you mount an Ext2/3 partition, and shows all the partitions on my physical drives. I'm assuming that if I had a partition formatted in Ext3 I could just mount if from there.

But the file system I want to mount is not a partition - it's just a file! And I can't see any way in Ext2 IFS to select this file and mount it so that it will become accessible under Windows.

I'm probably missing something really basic here, but as I said I'm new at this. Could someone with a bit of Linux/Windows experience point me in the right direction? Thanks!

40hz:
Hi:

The short answer is - you can't.  :(

You can't mount the Puppy file system because it doesn't exist in the same manner as it would if Puppy were installed on a real drive partition. It's being emulated by QEMU. The Linux 'drives' you're trying to mount don't 'exist' as Linux partitions unless QEMU-Puppy is running. The rest of the time they're just part of the data file used by QEMU.

The QEMU-Puppy website has a better writeup than I'm giving you. You might have missed it, so I'm quoting it below:

2.2. QEMU

From the site: "QEMU emulates a full system (for example a PC), including a processor and various peripherals. It can be used to launch different Operating Systems without rebooting the PC or to debug system code."

In other words: QEMU is a virtual machine. A virtual machine is a program that acts like computer hardware. In such a virtual machine, you can install an OS (Linux, Windows, BSD, whatever). This OS "sees" a processor, which is the real processor (I'm lying...), "sees" a hard drive, which is a big file on the host machine, "sees" a network card, which is emulated by QEMU, and so on. After shutting down the virtual machine, all that's left on the host (or USB memory stick) is just one big file: the virtual hard disk.

From the point of view of the host OS, QEMU is just a simple program which allocates a lot of memory, eats a lot of CPU cycles and opens and closes a couple of files. That's it.
--- End quote ---

When you think about it, you've answered your own question:

the file system I want to mount is not a partition - it's just a file!
--- End quote ---

Yup. That's exactly right. :)

Jimdoria:
OK 40Hz - I think I've got it.

A question though - one of the reasons I went with QEMU Puppy is that it has the ability to boot "bare metal" Puppy Linux from the thumb drive. I've done this successfully. In this scenario (AFAIK) QEMU is not involved at all - it's just Puppy running. So Puppy must have the ability to access the volume file natively, outside of emulation.

I was guessing that using the .3fs file as a mountable storage volume was something you could generally do in Linux. There are analogs in the Windows world. TrueCrypt works the same way, mounting a single encrypted file as a storage volume.

Is this feature specific to Puppy Linux? That would explain why it isn't widely supported.

40hz:
I'm not the world's greatest authority on Puppy (I mainly use it as a rescue OS for a non-bootable system) but I would guess it is unique to that distro.

Your best bet would be to go up on the forums and ask the real pros. Link for the main forum page can be found here:

http://www.murga-linux.com/puppy/index.php?f=4

This thread might be of interest if you just want to boot from the USB but keep your files on a specific PC:

http://www.murga-linux.com/puppy/viewtopic.php?t=20984&search_id=1413374969

BTW: Welcome to Linux! :Thmbsup:

Armando:
Also Puppy Linux' author seems like a nice guy. He might be willing to help.

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