[dundee] Virtual machines can trash your system

[Bruce Stewart]

On Saturday 11 August 2007 00:03:06 gordon dunlop wrote:
> Hi All,
>
> I am just about crying here. The story is that at long last I decided to
> upgrade my Fedora 6 to Fedora 7. I waited this long because fedora 6 is
> my default system holding all my multimedia, server, virtualisation and
> (most importantly ) my wife's document  systems.  I decided that instead
> of upgrading via YUM or the  downloaded DVD, that I should create a new
> system with the  proper partitions (that I should have done previously),
> i.e. having the operating  system spread out over three partitions;
> namely /, /home & /var where  /home  would take care of the multimedia
> and documents, and /var would take care of the server and virtualisation
> systems, comprising of 80% of the disk space. Why I did not want to do a
> direct upgrade was that I was transferring from a 32-bit system to a
> 64-bit system, so by doing a clean install of Fedora 7 whilst
> maintaining a fedora 6 system , I was going to transfer the data from
> Fedora 6 To Fedora 7 when I satisfied that everything on Fedora 7 was
> running O.K. I used a partition manager to manipulate my two SATA disks
> to create the space for the Fedora 7 partitions and moving the Fedora 6
> partition i.e. data movement. After this was done I booted into my
> Ubuntu partition, I knew GRUB on my Fedora 6 partition would not work. I
> got a fsck superblock error in Ubuntu (because the Fedora 6 partition
> had been moved), this was rectified by editing fstab to set the
> default  binary of the Fedora 6 partition to 0 0 rather than 0 2. I
> rebooted where the Fedora 6 partition was picked up by Ubuntu, and using
> the  GRUB editor  reinstalled  GRUB into my Fedora 6  partition with the
> commands:
> GRUB>  root (hd1,6)
> GRUB>  setup (hd1,6)
> GRUB> quit
> hd1,6 is the equivelant of /dev/sda7. I rebooted and  went into the
> Fedora 6 system via GAG  boot manager. The menu came up and the system
> was initiated, when it came to the file system check it went into fsck
> mode (as was expected) It took about  30 minutes  with a lead weight on
> the Y key for it to go through its routine to change the inode errors.
> It came up with at the end errors it could not correct with root inode
> not a directory. I eventually rebooted and went back into the Fedora 6
> partition where the GRUB prompt came up and I could not re-install GRUB
> due to superblock errors nor could I mount this partition from other
> Linux partitions. I was scratching my head trying to work out what was
> going on, then I realised that my Windows XP virtual machine (20GB) is a
> NTFS file of 20GB.  Here I have a file of 20GB of the NTFS file system
> within an EXT 2/3 system. This is why there were problems in correcting
> inode errors based upon the ext2/3 fsck system where the Virtual XP file
> was preventing this. The virtual Windows XP machine cannot see the file
> system of Linux (It has an Aspberger Syndrome complex where it thinks it
> is important, but it is only a lowly piece of shit within the system and
> does not understand about hierarchies). I now cannot mount the Fedora 6
> partition, nor find a way to either destroy or move this XP virtual
> machine. I have diagnostic tools, but they only deal with Linux or
> Windows file systems, not both. This brings to the conclusion that there
> will be problems in large IT environments where heterogeneous systems
> using virtualisation systems, especially in looking at Process
> Migration. So, if anyone can help me I would be very grateful, not that
> I care much for these large IT environments, it is more of how can I
> tell my wife that she cannot access her documents. Anyway no more
> googling for the answers tonight.
>
> Gordon
>
>
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The VM image is just a file, like a an OO.org Doc, or an .mpg, so it doesn't 
matter what is in the image file. So unless you have created the VM on a bare 
(filesystemless) disk, whatever fsck tool you are using should be for 
whatever filesystem the VM image file is on.
You may have a base filesystem problem, ie the disk itself is actually fracked 
or the filesystem is damaged in such a way that it is not repairable.
Or you may have a VM image problem, ie the disk image inside the VM is 
damaged, so it needs to be fixed by XP's own tools.

Bruce S.