The bigger ones definitely required decent periodic maintenance. Typically you'd contract DEC or a third party to come out semi-annually to vacuum things out, apply field fixes (yes, run wires on boards and the backplane), and run hardware diagnostics.
There were a lot of wire-wrap connections on those things. If they had been done right you were good. Done wrong, and your system was haunted until someone found the loose wire. We had an 11/45 with a flaky Unibus bay that could be "fixed" with a little percussive ablation. Finally got DEC to get serious about the problem, and they spent several days tracking down a bad socket.
I don't miss wire wrap. At all.
We have it good these days. Rack a bunch of servers, run them hard for years with only DIMM replacements or maybe the odd SSD, and recycle them once the bathtub failures start edging up. I don't want to think about the comparable compute power; my wristwatch runs rings around that 11/45. We live in the future.
At least one RSTS/E release amusingly came with patch notes that included wire wrap instructions. I distinctly remember a great deal of grumbling when the patch caused issues and the downgrade included undoing the wire wrap patches. If you thought sharing your screen and coding or debugging was high pressure, imagine pulling out one of the drawers holding your computer's guts and dealing with this while a room full of people hovered over your shoulder. https://upload.wikimedia.org/wikipedia/commons/a/ae/PDP-11-3...
There were a lot of wire-wrap connections on those things. If they had been done right you were good. Done wrong, and your system was haunted until someone found the loose wire. We had an 11/45 with a flaky Unibus bay that could be "fixed" with a little percussive ablation. Finally got DEC to get serious about the problem, and they spent several days tracking down a bad socket.
I don't miss wire wrap. At all.
We have it good these days. Rack a bunch of servers, run them hard for years with only DIMM replacements or maybe the odd SSD, and recycle them once the bathtub failures start edging up. I don't want to think about the comparable compute power; my wristwatch runs rings around that 11/45. We live in the future.