I "worked" (for various starving student hobby definitions of "work") on a Univac SS-90 which had a 17,000 RPM drum for main storage (50,000 decimal digits!). It took 12 minutes to spin up, and the manual warned that once power was turned off and it started spinning down, you had to wait an hour before turning power back on. (All from memory.) We often wondered what would happen when the bearings seized up; would the entire mainframe (probably a ton or two) twist or thump? One of us later was using it when it did fail, but it failed slowly, just being harder to start or slower to spin up, I forget now, and one day just wouldn't start.