Pertec Tape Drive Interface Musings

[Chuck Guzis]

On 08/03/2015 09:54 PM, Eric Smith wrote:
> On Wed, Jun 10, 2015 at 9:40 AM, Dennis Boone <drb at msu.edu> wrote:
>> The main limitation seems to be that it's hard to get the (broken)
>> data from a block that had a read error when using SCSI hardware.
>> There's probably a way around this if one digs into lower layers of
>> SCSI magic; I haven't gone looking.
>
> Nothing using standard SCSI commands, unfortunately. Might be some
> vendor-unique stuff.

I find that Linux/BSD SCSI tape handling gets really strange when errors 
occur.  If you're willing to run MSDOS with an appropriate ASPI driver, 
I can send you a utility that I know works--if an error occurs, the bad 
block is padded out to the same length as the preceding one, so the 
overall structure is less likely to be disturbed.

One of these days, I'll port the SCSI interface of the program to sg(), 
but not right away--too many other irons in the fire.  But you're 
welcome to the source code.

One of the things that I don't like about SCSI tapes is precisely the 
error handling--very often, you get no data returned, where a native 
Pertec interface might have given you something.

--Chuck