Does anyone/museum test disk packs?

Chris Zach cz at
Thu Mar 17 08:33:08 CDT 2022

Modern disks still have a filtration system and airflow within the disk. 
Air usually gets sucked from the edge then through the spindle and out 
the center. In this case I think the spinning created a lower pressure 
area where the heads were, resulting in the heads flying too low.

I'll re-look at the RL02 but I believe air was not pulled in from 
outside but recirculated from behind the heads under the unit to the 
center spindle where it came out, into the center of the pack and across 
the heads. Closed system when the lid was closed.


On 3/17/2022 9:27 AM, Paul Koning wrote:
>> On Mar 16, 2022, at 10:28 PM, Chris Zach via cctalk <cctalk at> wrote:
>>> I vividly recall a log by an operator who had a bad CDC 844 pack who
>>> proceeded to destroy 5 drives and 3 additional packs. It was detailed
>>> enough that it read like Gerard Hoffnung's "Bricklayer's Story".
>> When I was testing one of my RL02 drives I had a head skid on the disk. Problem was the air filter was so clogged there wasn't enough air to allow the heads to fly.
> Huh?  The way I've always understood it is that heads fly from the air entrained by the disk surface as it spins, not from air blown through the drive via the air filters.  And clearly that is true for modern drives, since they are sealed.
> 	paul

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