[OLUG] On backing up Windows with Linux

[Phil Brutsche]

A long time ago, in a galaxy far, far way, someone said...

> Windows was on the 2 gig, and Linux was on my 10. This was great
> because whenever I needed to reinstall Windows (often) I just
> unplugged the 10 gig, since Windows 98SE won't install if Linux is
> present (bastards...). But now I had to migrate my system over to the
> 10 gig exclusively, so I'm pretty much in the same situation as mesc
> was. I want to create an image of my Windows partition, now that
> everything just freshly installed and working, and then burn the image
> to cd. Unfortunately, the Windows partition is just over a gig, and I
> don't feel like breaking it up and using two or three discs. My
> question is: if I use mkisofs to create an image, and I use this to
> restore my Windows install, will it be bootable?

That depends: are you making a image of the raw partition, or just the
file system layout and the files?

If it's just the layout and the files, what you and mesc are trying to do
won't work.  When DOS/Win9x load, what happens[1] is

1) Master boot record loads from sector 0
2) Master boot record loads and executes a partition boot record
3) Partition boot record loads an arbitrary set of disk blocks into
   memory, and executes them.  This arbitrary set of disk blocks is
   represented in the file system as io.sys (or the equivalent, if you're
   not using MS-DOS).  io.sys understands the FAT file system, and can
   load the MS-DOS kernel proper by reading the file system to know where
   to get the necessary file (msdos.sys).

You'll have trouble restoring Win98 to working condition because 1) you
won't be putting the partition boot record back and 2) if you did put the
partition boot record back, the file io.sys isn't where it's supposed to
be for the partition boot record to load it.

If you're making a raw image of the partition, it should work fine.  Just
make sure you compress the image before you write it to CD.

> Secondly, my 2 gig isn't any good now because sector 1 went bad. But
> I'm wondering, could I still use it for storage if my mbr is on
> another disk? Or does the Fat/Inode block info need to be written to
> sector 1?

I would imagine that that depends on how you partition the hard drive, as
well as the condition of the drive.

First, make the 10GB the primary master, and move the 2GB elsewhere; that
way the boot record won't be an issue.  Second, sector 1 would only be
used if it's contained in a partition.  IMO you should be OK if the
partiton you're using doesn't have sector 1 in it - ie make 2 partitions,
.5 meg and a second filling the rest of the disk, and only use the second
partition for storage.  The .5 meg is an arbitrary number; you only need
to avoid sector 1.  Partition information is stored in sector 0 (are we
counting the same way here?), so there should be no problem using the
disk.

If, however, you mean the _very first_ sector on the hard disk when you
say "sector 1", then all hope is lost.  It's probably not heavy enough to
be a doorstop; it'd make a nice paperweight, though.  I also hear the disk
platters make very nice coasters (for coffee cups).

[1] Note that this is my (potentailly flawed) understanding of how MS-DOS
is supposed to boot.  You really need to ask someone who's worked on the
internals of DOS more recently than I;  The people working on FreeDOS
would make an execellent source if information.  Their web page is
http://www.freedos.org

-- 
----------------------------------------------------------------------
Phil Brutsche					pbrutsch at creighton.edu

"There are two things that are infinite; Human stupidity and the
universe. And I'm not sure about the universe." - Albert Einstein


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