Years ago I worked for Systime computers and at one time I did the UK repairs for CDC SMD drives. As far as I remember there were two that you could desk or trolley mount and one high capacity drive that came trolley mounted. I think they might have been 20 and 40mb with the trolley mounted one being maybe 80mb. Even the lower mp count ones were so heavy it too two of us to lift them. One day when there was no one to help me I tried to pick an SMD drive up by myself and as a result I have a back injury to this day. The metal bashers worked further down in same room and they hated us electronic guys (they thought we were too posh and privileged) and as my station was near the walkway they used to turn the kit I was soak testing off as they walked by which was nice of them.
Later when I worked for DPCE the first batches of "Winchesters" arrived and I think they were 20mb, anyway they lost half their capacity once you mapped out the bad tracks.
It's amazing how far we've come.
Hope you enjoyed the history lesson