Where are virtualBox guest data saved in the host system?
March 12, 2014 3:28 PM   Subscribe

Where are virtualBox guest data saved in the host system?

I'm new to VirtualBox. I installed guest system windows7 and Linux(Luna)on host Mac OSX 10.9.
I'm trying to find out where are the application files(like .exe.. ) and user data (like .jpg, .doc, .tar..) created in the guest systems saved relative to the host systems??
What are the absolute path/directory of the virtual C:/ and / ?
Or do they even exist and accessible ?? How does the virtualbox work on file systems?

To be specific about the question:
I backed up the whole mac with virtual machines to an external hard drive using Time Machine, in addition I backed up the Ova file.
With this hard drive in hand and a windows computer, can I access the user data created in the guest system (suppose that I have MacDrive installed so I can read the file system on windows )?

Can someone shed me some light on this? Thanks very much!
posted by pack2themoon to Computers & Internet (6 answers total)
In your home folder, you have a folder called "VirtualBox VMs", in which are folders for each guest OS. In each guest folder is (usually) a VDI file, which is the container that holds the OS, partitions and everything else.

Instructions for mounting VDI files in OS X as a disk image are available here if you are comfortable with the command-line.

For your Windows VDI, Mac OS X can read NTFS-formatted partitions. It cannot write to them.

For your Linux VDI, OS X cannot read or write ext-formatted partitions, so you'll need to do some extra work. The instructions outline what you'll need to do in this case.

For mounting VDIs from within Windows, here is some discussion.
posted by Blazecock Pileon at 3:39 PM on March 12, 2014

Short answer: your files are somewhere within the virtual hard drive you installed the operating system on, unless you've done something to enable the guest OS to save to the host OS's filesystem.

Longer answer: Virtual Machines don't work the way you think they do. When you use a VM, the VM host fools the guest OS into thinking it has a computer all to itself, with its own hard drive. This virtual hard drive is represented as a single file (typically) in the host OS, and is generally opaque (although there are some programs that can read them, if you look around).

Now, to solve your problem: I don't have direct experience with VirtualBox, but it looks like these instructions on sharing files between guest and host OSs in VirtualBox should get you started. Note that this will only work while your guest OS is running. If you want to access them offline, Blazecock's answer looks like a good place to start looking.
posted by Aleyn at 3:42 PM on March 12, 2014 [1 favorite]

Response by poster: Thank you guys!!

Blazecock: So does it mean that different VDIs for different operating systems have different disk format(how can it be)? ie., Windows7 VDI has NTFS, Linux VDI has linux format(what is it?), VDIs act like hard drives? kind of like an image, .iso file? sorry I actually don't know how iso file can wraps a disk into a file?

Aleyn: you answer helps clarified some concepts, thanks.
posted by pack2themoon at 3:59 PM on March 12, 2014

Different OSes often use different disk formats, yes. Windows prefers NTFS. OS X prefers HFS+. Linux likes ext3/4.
posted by Blazecock Pileon at 4:41 PM on March 12, 2014

I don't know Virtualbox, but I'll assume it's similar to VMware.

As for different filesystems (ie, running EXT4 filesystem on a Linux VM on a physical Windows host), the Windows host (generally) doesn't know anything about the filesystem in the Linux VM's virtual disks. Windows just sees them as a file (or a set of files), and can't see what's inside them, and doesn't need to. The VM is completely responsible for managing, reading and writing to it's virtualised filesystem.

As Aleyn said, there are tools you can use to access the VM's filesystem from the physical host, but they're kind of a "hack", for want of a better word, in that they typically require a piece of software in the VM (like VMware Tools) that can see the VMs filesystem, and also talk back out to the physical host.
posted by Diag at 2:53 AM on March 13, 2014

Response by poster: Thank you Blazecock and Thank you Diag, that helps a lot!
posted by pack2themoon at 9:55 AM on March 13, 2014

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