OT: How to debug ZIP drive

Skip Gaede sgaede at mediaone.net
Tue Oct 16 17:24:20 PDT 2001


Richard Lightman wrote:

> Misquoted from Skip Gaede on 2001/10/ 9 at 09:27 +0000:
>> Hi,
>>
>> I
>> have an internal ATAPI Zip drive that works fine under Windows. I cannot
>> read or do sustained writes (format) media in the drive under Linux.
>>
>> hdc: 98304kB, 96/64/32 CHS, 4096 kBps, 512 sector size, 2941 rpm
>>
>> hdc: hdc4
>> VFS: Disk change detected on device ide1(22,4)
>> hdc: hdc4
>> ide-floppy: hdc: I/O error, pc = 28, key = 5, asc = 21, ascq =  0
>> end_request: I/O error, dev 16:04 (hdc),sector 196496
>> ide-floppy: hdc: I/O error, pc = 28, key = 5, asc = 21, ascq =  0
>> end_request: I/O error, dev 16:04 (hdc), sector 196498
>> ide-floppy: hdc: I/O error, pc = 28, key = 5, asc = 21, ascq =  0
>>
> This problem is on the last 56K of the drive. I suspect that
> windows never writes to this part (unless you have less than
> 56K of free space).
> 
> Try repartitioning to avoid the last bit & see if that
> solves anything.

I'd like to restate what I know about the ZIP drive, now that I've done 
some more homework.

There are two drivers which can be used to talk to the drive, SCSI 
(emulation) and ide-floppy. Of the two, the ide-floppy seems more 
sophisticated, as I can configure the drive as either a large 95 cylinder 
floppy, or as a small 96 cylinder drive with a partition table (in BIOS 
setup). The ide-floppy driver notices the difference -- the SCSI emulation 
still sees the drive as 95/64/32 no matter what.

The mke2fs program does succeed, eventually, in formatting the partition, 
but it missed about 112 interrupts during the format operation, causing the 
driver to do a RESET operation for each one. The ide-floppy driver uses 
packet writing technology, and has been revised several times this year. I 
think it isn't quite ready for prime time yet under the 2.4 kernel. For one 
thing, it took almost two hours to format an 85 MB partition, compated to 2 
minutes under Win2000 to do the whole 95 MB.

So, it works, sort of, and it's slower than molasses. There are a bunch of 
tweakable parameters in /proc/ide/hdc/settings. I have not found much in 
the way of documentation on them, however.

I may see if I can grab the ide-floppy driver in the 2.4.2 kernel and try 
recompiling that one.

Suggestions welcome,
Skip
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