Buffering error 8" floppies

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Buffering error 8" floppies

Post by adamsabi » Mon Jan 29, 2018 10:20 pm

I have been experiencing some errors when creating preservation stream files for 8" floppies using a Shugart 851. It seems to work until the last few tracks, usually track 77 and 78.

The errors that show up in the GUI read:

Buffering error
Stream read error
Device control command failed
Device not connected or not initialized
Read failed

In the log file, there are more than a few tracks that state 'The streaming device reported a buffering error'

Any help here is greatly appreciated! I've attached a screenshot. Here is a link to the log file: https://utexas.box.com/s/e9v3x9gun59fla ... 89oqbj2qtv

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Re: Buffering error 8" floppies

Post by ZrX » Tue Jan 30, 2018 12:08 am

8" floppies usually contain only tracks 0-76, so 77+ would cause various problems.

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Re: Buffering error 8" floppies

Post by brightcaster » Tue Jan 30, 2018 9:35 am

You can ignore the buffering error, as it is due to busy USB connection! DTC corrects this automatically with a retry (as you can see in the suplied log also)...


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Re: Buffering error 8" floppies

Post by IFW » Tue Jan 30, 2018 1:12 pm

You probably get very quick/short flux reversals on unformatted tracks, starting with track 77.
If you ever see READ OPERATION FAILED it means DTC has given up on reading that track, due to the number of retries already attempted.
What you see in the log is that some tracks could not be sampled - that's why they are marked red in the GUI.
Since these disks contain nothing on the affected tracks, it does not matter, but you might try to:
1, make sure the KF board is connected to a direct USB port (on the mainboard), ie not after an external or internal hub
2, make sure that no other device shares the same USB port with KF (so there is no bandwidth reserved for them even if they are inactive)
3, increase the number of retries
4, switch the drive to 300 RPM - this will make the drive rotate slower, and in turn making the sampled flux reversal periods longer, so "easier" to sample/transfer. It makes no difference to DTC as it uses time domain conversions anyway.
+advanced (NOT recommended unless you have experience)
5, clean the drive head
6, replace the filtering in the drive, so it would generate less noise

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Re: Buffering error 8" floppies

Post by ZrX » Tue Jan 30, 2018 3:19 pm

If you hear clanking noise after track 76 that means your drive can't step any further and should then add -e76 to the parameters to avoid possible damage to the old drive.

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