TAPE/DISK Interface troubles ?? (help!)

[Howard Leadmon]

 I have a very interesting situation over here that confuses the daylights
out of me, and hope somebody might have some ideas. I have just installed
a Bell Technoliges tape drive in my 80386 machine (60meg 1/4" streamer)
and this is were the problem begins. When attempting to backup the data
from my 130meg PRIAM drive, the drive will generate errors about accessing
the disk, and of course UNIX get's ticked off at that and goes belly up on
me. After carefully observing the problem I have discovered that it only
happens when both the tape unit and the hard disk are both attempting an
access that the same time (all interupts are OK). To verify this I used tar
(not Bell's special utilites) with a very small blocking factor, and this
made things slow.... but it reduced the chance of conflict. I haven't come
up with a way that I can start a backup without having both devices doing an
access at the same time, but this it what I have been able to deduce from
using different modes. Anyway what happens it that the HD goes through the
restart and calibrate procedure (as described by Priam) when the error
occours, and UNIX won't tolerate the delay. I have done very very heavy
accessing on the drive, and handle a lot of mail/news, and the drive works
without a flaw unless I use the tape drive. Also I have made backups on
floppy before, but backing up a 100meg of data on floppy is terrible!!
Does anybody have any idea as to what might cause this conflict, and if
so any possible solution ?? I really need to get the backup working, as
the potential data loss from not backing up is scary... [help!]


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