Formatting non-DEC disks using zrqch0...

[Curtis H. Wilbar Jr.]

Josh Dersch wrote:
> The RD53 drive in my 11/73 has finally gone to silicon heaven, after a 
> brief resurrection.  Given the reputation these drives seem to have, 
> I'm not too surprised.  So a few nights ago I dug through my stacks of 
> ancient hard drives and found three possible candidates for replacement:

RD53... Micropolis 1325 I believe.  I ran one of these (I believe it was 
an RD53
actually... not just a generic 1325) in a PC years ago.

It one day started not wanting to initialize... startup... think think, 
chunk chunk,
spin down....

With nothing to lose, I began to experiment...

What I found was that it couldn't apparently locate track 0.  If the HDA 
os opened,
it has two rubber? bumpers for the extreme ends of head motion.  One for 
track 0
and one for last track ?

They look something like:

 ----
|         \
|____ /

with an adjustable slide 'hole' in the middle.

What I'm guessing went wrong is that the material hardens and/or shrinks 
with age.

By carefully tweaking the adjustment on this item to allow a mere few 
thousands of
an inch inward... the drive started initializing fine every time.

I did not use the drive much after that, so how drive longevity would be 
effected by
the introduction of contaminants into the HDA assembly I don't know (I 
of course
don't have a clean room :-) ).

However, if you have a fairly clean space, and can work carefully as 
such not to
stir up contaminants, you may be able to rescue your RD53.

Another problem I read of someone having a problem with an RD53 had to do
with the brake solenoid assembly needing adjusting as the brake pad was 
dragging
(it is located under the circuit board on the bottom as I recall... no 
inside the HDA).

-- Curt

>
> - A Microscribe 6085, which seems to have the same drive geometry as 
> an RD53
> - Two Seagate ST-251s, which seem to be identical to an RD32
>
> All of these are in "unknown" condition (I haven't used them in 
> years), but spin up without making any evil noises and are recognized 
> by the RQDX3 controller.  To the best of my recollection, all three 
> were formerly used in PCs.
>
> I've used zrqch0 (booted via vtserver) to format all three of these 
> disks.  In all three cases the formatting appears to be successful -- 
> the drives format for a few minutes, then go through three 
> verification stages for another 20-30 minutes.  During this time I can 
> hear the heads being stepped, and the drive access light blinks.  At 
> the end of the format no errors are reported.
>
> I'll note that in order to do the format on these drives, I had to go 
> through the process manually (as opposed to the "AUTOFORMAT" mode of 
> zrqch0) -- for the Microscribe this was because zrqch0 didn't 
> recognize the drive (showed up as "unknown"), for the ST-251s this was 
> because the fault tables could not be read off the drives.  I suspect 
> this may have something to do with the issue I'm seeing, but of course 
> this is pure speculation.  I've tried various permutations of the 
> formatting options, but I've had no joy there.
>
> After formatting the drives, no other utilities seem to be able to 
> make use any of the drives -- running the disk exerciser (zrqah0) 
> fails after the first test step (and after a very small amount of disk 
> activity) with an error similar to the below (this varies slightly 
> based on the test being run):
>
> FATAL I/O ERROR
> * DISK 0 WENT OFFLINE
> * SUB_CODE: NO VOLUME MOUNTED OR DRIVE DISABLED BY SWITCH
> * COMMAND: READ_COMPARE
>
> Interestingly, 2.11BSD's 'disklabel' is able to partition and write 
> the label to the disk.  Mkfs, however, fails with:
>
> ra(0,0,0) error op=A2 sts=23
> write error 3
> Exit called
>
> I've tried this with two different RQDX3 controllers with the same 
> results (and these controllers worked fine with my RD53 until it 
> failed).  Is there a magic step I'm missing?  Is what I'm attempting 
> to do (use non-DEC drives) not possible?  Any ideas or suggestions?
> Thanks for any help here...
> Josh