Subject: Re: Hardware trouble question...
To: Greywolf <>
From: Dave Tyson <>
List: current-users
Date: 10/08/1999 09:17:40
On Thu, 7 Oct 1999, Greywolf wrote:

>I have a 4G SCSI drive whose problem is that it won't spin up all the
>way; i.e. the starter motor keeps kicking in, giving up after the 10th
>attempt to get to speed.

Are you sure its just the motor ? Often there is an interlock which
powers down the motor if the heads fail to engage...see below

>Can anyone suggest to me a method for fixing this aside from a) tossing
>it, b) sending it back to be refurbed, or c) getting a new drive?  It
>seems a nice drive (h/h drive).  I'd like to put it in and decommission
>some of my older drives.

If the drive hasn't been used for a long period and then it fails to
spin up its usually due to the heads sticking to the disk surface. This
was a particular problem with 2/4gb IBM drives about 5 years ago, but I
have seen it on several other makes. In the good old days the heads
used to retract to a safe area (the landing zone), but nowadays the
heads just slow down and come to rest on the disk surface. To avoid
wear the disk surface is coated with a antifriction layer (oil!). Over
the years this tends to thicken and get tacky and this can cause the
heads to stick if the disk is left for a long period. The head drive
assembly does not have the grunt to break the bond and sometimes can 
be heard to make a ticking sound as it repeatably retries - often after
10-20 attempts the drive powers down.

Hold the disk firmly in both hands with the (platter) in the vertical 
plane and swing the disk firmly in an arc. This will often break the
bond and get the head to move a little - sufficient to allow the 
drive motor to get it to move when powered up. You may need a couple
of attempts. IBM's fix for the problem was to supply a disk scrubber
which you ran via cron at 3.00am - It did repeated seeks across the 
surface (in engineering diagnotic mode) to remove the crap (or at least
spread it about a bit more)

"works for me"

Dave Tyson                      Phone: 0151-794-3731
Computing Services Dept         Fax:   0151-794-3759
The University of Liverpool     Email:	
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