We had a Tandem TXP system we installed in '85. It had an even 10 300mb (RCA) disc drives. I pretty much threatened to break the fingers of anyone who opened the drives. If you left the pack in the drive and kept it closed, they would be ok for years. Our old General Automation system had 20mb drives (later upgraded to 80) and they swapped packs twice a day. We had head crashes all the time on them.