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:
Re-reading bad sector disks?:
IFW gave a good description of the difference bettwen the Retry and Retry Cycle commands:
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-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)
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)
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?IFW wrote: ↑Thu May 21, 2015 9:19 amActually, 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.
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?
Does this mean that 10 revolutions is better than 5? And 20 revolutions better than 10?
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?