[Info-vax] ODS-5 data/file recovery

[Simon Clubley]

On 2013-02-15, MG <marcogbNO at SPAMxs4all.nl> wrote:
> Recently, during a strangely botched file transfer via CIFS, a file was
> somehow removed in the process (and wasn't successfully transferred
> either, with nothing left as a result) and I don't seem to be able to
> restore it through the usual methods (e.g. "DFU UNDELETE").
>
> I've also tried to see what I could do, via "ANALYZE /DISK" and (later
> also "/RMS", although the latter was rather pointless, as it's a Zip
> file).
>
> Are there any alternatives for data/file recovery?  Besides expensive
> data recovery services.  It's an ODS-5 volume.  I'm for now making an
> image back-up for the disk, I also noticed that I could see string of
> the file (or filename, rather) that became 'lost' (whilst mounted
> 'foreign') and that may be a good starting point.
>

Image backup will not preserve your disk in this case; it only gives you
a functionally equivalent copy of the disk for files which have not been
deleted.

What you want is a physical backup of the disk.

> Any tips, advice, pointers and help are most welcome.
>
>   - MG

It's been a very long time since I wrote a ODS-2 reader (about a decade
ago) so this is from memory, but I would start by running down indexf.sys
and see if you can locate the file that way.

If you can, follow the allocation chain and see if the blocks still
belong to your file. As it's a zip file, even if some of the blocks
in the middle may have been reused, you may still be able to extract
some data from the zip file if the zip index itself is intact.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world