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Many if not all of these mainframes have been fully upgraded or at least serviced due to hardware failure while still running. I’m not entirely sure how you de
by dogma1138 7y ago
Many if not all of these mainframes have been fully upgraded or at least serviced due to hardware failure while still running.
I’m not entirely sure how you define uptime for these machines if none of the original parts are still there.
- pinkfoot 7y agoTrivially: 100%
- verisimilitude 7y agoPhilosophers ask a similar question to yours: https://en.wikipedia.org/wiki/Ship_of_Theseus https://en.wikipedia.org/wiki/Ship_of_Theseus
- dogma1138 7y agoI was hinting at that, which is why we should define an uptime of a system rather than a machine because with distributed systems that uptime of the system isn't dependent on the uptime of a single "machine" and a mainframe is a distributed system even if it's in a single rack. The question is then where you define the boundaries of a system and it's uptime. At least from my recollection for mainframes they defined uptime based on the execution of batch jobs and availability of services not the OS/Hardware which if it crashed often involved Big Blue coming to investigate WTF happened and how it happened since System Z machines are designed with so much redundancy that you can swam RAM modules without interrupting the workflow. Today with RAIM (RAID for Memory) IBM System Z machines even support an entire memory channel dying without interruption.