Slow ESDI transfer rate - why?

Frank I. Reiter frank at
Fri Aug 25 01:13:33 AEST 1989

One of our machines is running SCO Xenix 386 2.31 on an intel motherboard.
Some time ago we installed a Miniscribe 9380 ESDI drive with a DTC controller
and contrary to expectations, it seemed slower than the RLL drives we were
replacing.  At the timewe didn't have another machine to compare with, and
there were more pressing matters to attend to.

Now that I've tested it against another machine with an RLL drive I am amazed
to find it more than 5 times slower!   We are using a different hard drive now,
and have tried swapping controller cards.

this command:

time dd if=/dev/rroot of=/dev/null bs=1024 count=1000

takes 18.7 seconds to run. Reformatting with an interleave of 2, 3, and 4
made things slightly slower each time.  (We are back to 1:1 now).

Other hardware in system:  Everex tape drive, Arnet smart-8 board, AST 4-port
board, generic monochrome card, several memory boards.

Both DTC and the drive manufacturer were mystified.   Has anybody else seen
this problem?
Frank I. Reiter              UUCP:  {uunet,ubc-cs}!van-bc!rsoft!frank
Reiter Software Inc.                frank at,  a2 at mindlink.UUCP
Langley, British Columbia     BBS:  Mind Link @ (604)533-2312, login as Guest

More information about the Comp.unix.i386 mailing list