Kryoflux Flippy Disk Preservation Commands

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JasonCA
Posts: 32
Joined: Tue Oct 11, 2011 3:37 am
Location: California

Re: Kryoflux Flippy Disk Preservation Commands

Post by JasonCA » Sat Jun 09, 2018 9:12 am

Using the Flippy and Double Sided dump commands, I'm still dumping disks so I have enough to play with.

Question: What to do about the failed disks though? Does anyone have a rule of thumb for how the disks should be Re-Dumped when dumps have Bad Sectors found?

Below are some useful links I've run across touching on this subject.

retry missing sectors:
https://forum.kryoflux.com/viewtopic.php?t=1003

Re-reading bad sector disks?:
https://forum.kryoflux.com/viewtopic.php?t=191

IFW gave a good description of the difference bettwen the Retry and Retry Cycle commands:

Code: Select all

-t<try> : set number of retries per track, min 1 (default 5)
-tc<try>: set number of retry cycles per track, min 1 (default 2)
He made mention to this here:
IFW wrote:
Fri May 22, 2015 12:11 am
So the total number of retries per track is -tc * -t.
e.g. for t=5, tc=2 you get the following retry pattern
R, R, R, R, R, C, R, R, R, R, R
The above makes perfect sense! However, I've been also curious how the revolutions play into retrying bad tracks?

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-r<rev> : set number of revolutions to sample (default by image type)
IFW also made some mention to this here:
IFW wrote:
Thu May 21, 2015 9:19 am
Actually, DTC tries to collect a good read of a sector from any of the revolutions sampled at once. So if it did not succeed, the most likely case is that the revolutions sampled were not enough to have a good read of some sectors on any of the revolutions. You can change the revolution number using -r, by default it's 2, unless you specify a stream file as output in which case it's 5.
My understanding of this is that it seems the error correction merge analysis for bad tracks are done only between the set of revolutions? For example, if -r is 10, then will DTC analyses the 10 revolutions, attempt to merge them to determine a good read for that track? :)

And what's considered a revolution? Assuming -r is 5, then is that 5 good revolutions? Or, 5 revolutions with good and bad tracks? Or is that 5 revolutions before a Retry or Retry Cycle takes place? It seems that after each Retry or Retry Cycle, the 5 prior revolutions are abandoned and 5 new revolutions are obtained. If a good Track Read can be obtained from the 5 revolutions, then those 5 revolutions are saved and DTC will move onto the next Track? Is that sort of how it works? :D

Does this mean that 10 revolutions is better than 5? And 20 revolutions better than 10? :idea:

Maybe after 20 revolutions, if the track can't be read it's really hopeless it will ever be read correctly? At what point should someone give up on a track? How many revolutions are too many for a BAD Track? Is there a rule of thumb I should follow :?:

Is larger revolutions (-r) better before a Retry (-t) and Retry Cycle (-tc)? Or, is it better to have a handful of revolutions (-r) and instead do more Retry (-t) and Retry Cycle (-tc) attempts? :?:

JasonCA
Posts: 32
Joined: Tue Oct 11, 2011 3:37 am
Location: California

Re: Kryoflux Flippy Disk Preservation Commands

Post by JasonCA » Thu Jun 21, 2018 6:23 am

I've not been able to find any documentation on what "bad" and "mis" mean?

Here's a sample of a bad track:

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08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
08.0    : CBM DOS: <error>, trk: 005, sec: 21, bad: 8, mis: 8, *H
bad:8 means what?
mis:8 means what?

Here's the consistency graph for this track:
track_graph_08.0.png
Track 8
Acording to the manual, it says:
In the consistency graph, even if there are inconsistencies, displayed in red, for example from a worn out disk, the full track is still recoverable as long as a line can be drawn from left to right over the green area around any red regions. A complete vertical red section blocking the green area from top to bottom becomes unrecoverable.
In the above consistency graph, you could draw a line from left to right. Therefore, is this track really bad? If it is, then is there any way it can be recovered since a line can be drawn from left to right? However, if the track is good, then does that have something to do with what "bad" and "mis" mean despite CBM DOS: <error> being reported?

For the three horizontal bands, what is the significance of thicker horizontal bands?

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mr.vince
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Re: Kryoflux Flippy Disk Preservation Commands

Post by mr.vince » Mon Jun 25, 2018 9:02 pm

mis: 8 (missing sectors)
bad: 8 (bad sectors)

A missing sector is automatically bad, but not all bad sectors are missing.

Thicker horizontal lines indicate a weaker signal with timings ok to good, whereas needle-thin lines are prefect, with very exact timing.

The disk is not bad at the flux level, but might very well be bad at the logical level. E.g. a protection might give good reads, but still generate an error when accessing a track - on purpose. CBM DOS is interpreting the data at the logical level.

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