Bad sector recovery using STREAM files?

All questions about how to use KryoFlux go here.
jdb2
Posts: 19
Joined: Sat Oct 06, 2018 7:49 pm

Bad sector recovery using STREAM files?

Post by jdb2 » Fri Nov 16, 2018 6:12 pm

I have some 3.5'' 1.44MiB floppies and I can image them fine using the Kryoflux's STREAM file format, but when I try to convert the STREAM files to an MFM sector image, *ALL* the blocks are bad.

Without shelling out a few $K to a data recovery service, are there any techniques which one might use to recover the data in the bad sectors? I can clearly see plenty of flux transitions in the scatter plot. If there is just a problem with the CRCs, then I'd be happy with the recovered data. If, on the other hand, there is a problem with the track and sector synchronization markers, then I guess I could manually "repair" the disk by modifying the STREAM file to include the correct markers?

Thanks,

jdb2

brightcaster
Posts: 145
Joined: Fri Nov 08, 2013 10:48 pm

Re: Bad sector recovery using STREAM files?

Post by brightcaster » Fri Nov 16, 2018 6:59 pm

If all tracks are bad it rather looks like choosing the wrong format to decode the stream for me. Can you upload the stream data anywhere to have a look on it?

You may also load the stream to the hxc-tool and have a look to the grafic analyze view. There should be a visible pattern at least.

https://hxc2001.com/download/floppy_dri ... r_soft.zip

David
Last edited by brightcaster on Fri Nov 16, 2018 7:41 pm, edited 1 time in total.

SomeGuy
Posts: 178
Joined: Wed Feb 18, 2015 8:18 pm

Re: Bad sector recovery using STREAM files?

Post by SomeGuy » Fri Nov 16, 2018 7:07 pm

Is there any chance you could post the stream file, or does it contain private information?

The first thing is to try and find out what is wrong. First of all, as a sanity check, can you properly dump other 1.44mb disks?

Do you have the density line set for high density? (Normally Logic high=low density and logic low=high density - sort of confusing)

In some cases I have had to specify the RPM value when decoding, you might try manually specifying 300RPM.

Does it look like there is any physical damage to the disk surface?

The HxC software tool can plot a nice graph of the disk surface from a Kryoflux stream dump. If there are scratches on the disks, or if the disk is in an unexpected format, it will be obvious rather quickly. If you can't post the stream file, perhaps you could post a disk view plot from that stream image? That might give some idea what you are up against.

jdb2
Posts: 19
Joined: Sat Oct 06, 2018 7:49 pm

Re: Bad sector recovery using STREAM files?

Post by jdb2 » Sun Nov 18, 2018 8:33 pm

Thanks for the helpful replies! :)

The problem is that I don't know what's on this disk, but I had it in a stack of uncategorized important disks so I'm not sure if there's personal information on it or not.

Note that a few of the sectors are not bad, as I originally said -- my mistake.

Here are the photos of the Kryoflux scatter plot and the track analysis from the HxCFloppyEmulator, respectively :

EDIT mr.vince: External links to photos removed. Please store locally. The forum allows for image uploads.

( EDIT : What is the above about? What's the point of the "[img]" bbcode tag if one can't use it? When I used it it didn't provide me with an option to upload an image, just a text box for a URL pointing to an image. I guess I'll upload the three images that were deleted as attachments. )
unknown-disk-kryoflux-plot-scaled-2-800_zpswncymlzx.PNG
unknown-disk-track-analysis-scaled-800-2_zps5cmutllt.PNG
Any help would be appreciated.

Thanks,

jdb2

EDIT : When I said that all of the sectors were bad, I should have mentioned that this was the case when I used a KryoFlux STREAM file as a source and an MFM sector image as the target. Sorry for any confusion.
Last edited by jdb2 on Fri Nov 23, 2018 9:06 pm, edited 2 times in total.

jdb2
Posts: 19
Joined: Sat Oct 06, 2018 7:49 pm

Re: Bad sector recovery using STREAM files?

Post by jdb2 » Sun Nov 18, 2018 8:43 pm

The links to the full sized images are here :

http://www.mediafire.com/view/bsjlakby6 ... t.png/file

http://www.mediafire.com/view/1dscd9pts ... s.png/file

Sorry for the omission. ( Note that the native resolution screencaps are quite large as they're 4K UHD )

jdb2

EDIT : Fixed high-res screencap links.
Last edited by jdb2 on Sun Nov 18, 2018 10:00 pm, edited 1 time in total.

brightcaster
Posts: 145
Joined: Fri Nov 08, 2013 10:48 pm

Re: Bad sector recovery using STREAM files?

Post by brightcaster » Sun Nov 18, 2018 9:51 pm

Okay side 0 looks great so for me (1,44 Mbyte MFM DOS-Disk as far as I can see). Have you visually inspected side 1 of the floppy surface? Could be spots of mold there. If so try to clean it with a bit of water on a q-tip before you use any isopropanol or similar! You may just open the slider by hand and rotate the disk with a ball pen putting into the little hole in the center metall part for inspection.

Keep in mind that every box in the kryflux gui represend a whole track. So if one sector is bad the box gets red even if the other 17 sectors may be okay. So a few spots of mold would be enough to give such a picture...

David

jdb2
Posts: 19
Joined: Sat Oct 06, 2018 7:49 pm

Re: Bad sector recovery using STREAM files?

Post by jdb2 » Sun Nov 18, 2018 10:02 pm

brightcaster wrote:
Sun Nov 18, 2018 9:51 pm
Okay side 0 looks great so for me (1,44 Mbyte MFM DOS-Disk as far as I can see). Have you visually inspected side 1 of the floppy surface? Could be spots of mold there. If so try to clean it with a bit of water on a q-tip before you use any isopropanol or similar! You may just open the slider by hand and rotate the disk with a ball pen putting into the little hole in the center metall part for inspection.

Keep in mind that every box in the kryflux gui represend a whole track. So if one sector is bad the box gets red even if the other 17 sectors may be okay. So a few spots of mold would be enough to give such a picture...

David
Thanks so much for the info! :D

I'll take your advice and inspect the disk(s).

Thanks,

jdb2

SomeGuy
Posts: 178
Joined: Wed Feb 18, 2015 8:18 pm

Re: Bad sector recovery using STREAM files?

Post by SomeGuy » Sun Nov 18, 2018 11:17 pm

On the HxC track viewer screen, select Disk View Mode and see what it plots.

jdb2
Posts: 19
Joined: Sat Oct 06, 2018 7:49 pm

Re: Bad sector recovery using STREAM files?

Post by jdb2 » Mon Nov 19, 2018 9:13 pm

SomeGuy wrote:
Sun Nov 18, 2018 11:17 pm
On the HxC track viewer screen, select Disk View Mode and see what it plots.
Thanks for the suggestion :)

Here is what it looks like in disk view mode :

EDIT mr.vince: External links to photos removed. Please store locally. The forum allows for image uploads.
unknown-disk-disk-view-mode-800-scaled-1_zpsh2qw3oc4.PNG
And the link to the high-res version :

http://www.mediafire.com/view/ho6a5eusi ... e.png/file

jdb2
Last edited by jdb2 on Fri Nov 23, 2018 9:08 pm, edited 1 time in total.

brightcaster
Posts: 145
Joined: Fri Nov 08, 2013 10:48 pm

Re: Bad sector recovery using STREAM files?

Post by brightcaster » Mon Nov 19, 2018 9:54 pm

Thats very very strange! Is this the same disk as you showed with the first screenshot having the bad sectors on side 1? In this picture everything looks perfect having no sectors bad!

David

Post Reply