Reading DOS/Windows Backup tapes
, this is the first really big programming project I've thought about
working on since college. I was happy there for a while,
just sitting back and not doing anything really challenging.
Then, in my usual way, I decided to see if there was anything I could
do with the big stack of QIC-2120 and TR-1 tapes I've got sitting
around with lots of really old data on them (going back to 1994).
I was recently inspired by a cheap purchase at the University of
Michigan's Property Disposition (the place they surplus stuff) and
found an IDE TR-4 drive. I'd also gotten a TR-5 through eBay but
found that the tape format was significantly different that it wouldn't
read the tapes I had at all. I've found the TR-4 to be similar
(though it does actually read something). So, I'm left with my
Iomega TR-1 drive (noisy as hell) and I also obtained a pretty nice
HP/Colorado T1000 some time ago. These are both floppy tapes and
thus pretty slow.
In any case, my investigations have led me to a pretty sweet site by Will Kranz
that has a project that will read QIC113 in the version Microsoft came
up with for their Windows 95/98 Backup application and MTF tape
After some monkeying around I found that unfortunately these wouldn't
read files from tapes created using dd. After some digging around
and also looking at the mtf
project, created by Alan
Stewart, I found that there doesn't seem to be anything like what
I want to do. mtf wants to read files directly from SCSI tapes
and seems to have difficulty reading from ftape drives and Will's
project focuses on reading just the files (as you would create them on
a disk for instance). Will also sent me a program that should
just read the backups from the tape. I think I want to try to
avoid that at the moment because I need to back another step and just
get data out of the tape format that it arrives in. Again, here
Will's site has been invaluable, pointing me to the QIC standards page
which has mostly what I'm looking for. Once I'm able to create a
straight backup file from the dd'd image, one of these other projects
(or even the original programs) ought to be able to read the file
straight. I will probably create some test files to test this
out, since I just put together a DOS/Win95 machine with the Iomega
attached. The HP/Colorado T1000 is attached to my primary file
server and is much more reliable and quiet than the Iomega POS.
Well, I might as well publish my notes so far. These two documents
reflect the information I've gleaned so far by just reading the QIC
standards documentation and using hexdump and hexedit. I would
welcome any comments on them.
Thanks, Will, for your help so far.
Last night I made an interesting
discovery. The only difference between the Microsoft Backup tape
images (bit-copied from a MS Backup tape) and the MS Backup disk files
(.qic) is the VTBL header information. I could easily see
converting tape images to disk files by manufacturing VTBL info.
I just don't think I have that many MS Backup tapes.
I am having a bit more difficulty with the Central Point backup
information. There seems to be less correlation between the tape
images and the disk files. I am also having difficulty getting CP
Backup to recognize my tape drive. It keeps giving me a divide by
zero error. I don't know if this is due to the relatively modern
hardware I'm attempting to use or if there is enough difference between
the Iomega Ditto 800 (TR-1) and the Iomega Tape 250 drives to cause CP
Backup to choke and die. I may just have to come up with
486 and see if I can't get something to work.