Bulk disk imaging and disk-format identification with KryoFlux

The problem

We have a large volume of content on floppy disks that we know are degrading but which we don't know the value of.

Considerations

  1. We don't want to waste time/resources on low-value content.
  2. We don't know the value of the content.
  3. We want to be able to back up the content on the disks to ensure it doesn't degrade any more than it already has.
  4. Using unskilled students to do the work is cost-effective.
  5. Unskilled students have often never seen "floppy" disks, let alone can distinguish between different formats of floppy disk. So we need a solution that doesn't require them to differentiate (e.g. between apple formats, PC formats, Amiga, etc).

Solution

  1. Make KryoFlux stream files using the KryoFlux hardware and software.
  2. Use the KryoFlux software to create every variant of disk image from those streams
  3. Use the mount program on Linux to mount each disk image using each variant of file system parameter. 
  4. Keep the disk images that can mount in Linux (as that ability implies that they are the right format).

Very rough beginnings of a program to perform the automatic format identification using the KryoFlux software and Mount are available here.

Issues with the solution

  1. When you use the KryoFlux to create raw stream files it only seems to do one pass of each sector. Whereas when you specify the format it will try to re-read sectors that it identifies as "bad sectors" in the first pass. This can lead to it successfully reading those sectors when it otherwise wouldn't. So using the KryoFlux stream files may not lead to as much successful content preservation as you would get if you specified the format of the disk before beginning the imaging process. I'm trying to find out whether using "multiple" in the output options in the KryoFlux software might help with this
  2. Mount doesn't mount all file-systems – though as this is improved in the future the process could be re-run
  3. Mount can give false positives
  4. I don't know whether there is a difference between disk images created with Kroflux using many of the optional parameters or using the defaults. For example there doesn't appear to be a difference in mount-ability of disk images created where the number of sides is specified or disk images when it is not and defaults to both sides (for e.g. MFM images the results of both seem to mount successfully).
  5. Keeping the raw streams is costly. A disk image for a 1.44mb floppy is ~1.44mb. The stream files are in the 10s of MBs

Other observations:

  1. It might be worth developing signatures for use in e.g. DROID to identify the format of the stream files directly in the future. Some e.g. emulators can directly interact with the stream files already I believe
  2. The stream files might provide a way of over-coming bad-sector based copy protection, (e.g. the copy protection used in Lotus 1-2-3 and Lotus Jazz) by enabling the use of raw stream files (which -i believe- contain the "bad" sectors as well as good) in emulators

Thoughts/feedback appreciated

By Euan Cochrane, posted in Euan Cochrane's Blog

26th Jun 2014  3:15 PM  11426 Reads  1 Comment

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