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by bluGill 1064 days ago
Years back (late 1990s) I worked with some mainframe people. They bragged that everything is hot fixable on the fly so they can apply security updates or replace broken hardware without rebooting. Then they admitted they schedule a reboot every 6 months anyway. Turns out the redundant backup power supply failed in at the same time and one hot patch was not applied to startup scripts and it took a week to figure out what was missing so the system booted again. By rebooting every 6 months they remember everything and so can get the system back up.

I probably have some details wrong in the story above. I worked with those people, but never on the mainframe. I think the point stands though, if you don't do something often it can't be done.
1 comments
wmf 1064 days ago
This doesn't surprise me. Mainframes aren't just about never failing; they have a whole culture, including ops, around providing availability in ways that actually work.
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tjalfi 1064 days ago
I've also heard of teams that shut down the mainframe for an hour during a time change. It's an easy way to avoid application issues for a small amount of downtime.
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nubinetwork 1064 days ago
We used to do this on several hpux servers at $dayjob. However 95% of those servers have long since been decommissioned, and the remaining server didn't actually need it to begin with. (It was really anything that had an oddball database that needed it)
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TylerE 1064 days ago
If it runs Unix is isn't a mainframe.

Only half joking.

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nine_k 1064 days ago
I would say it's 90% not joking.

A mainframe has hardware different enough to require a different approach to the OS.

Of course a modern variant of System 390 happily runs tons of Linux VMs.

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pjmlp 1064 days ago
Starting by having systems programming languages that actually have proper strings, arrays and bounds checking.
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reverius42 1064 days ago
What are some of those languages? I'm curious to learn more.
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pjmlp 1064 days ago
Several PL/I dialects e.g. PL/S and PL.8, BLISS, Modula-2, ESPOL/NEWP for example.

Also Pascal and BASIC compilers with several extensions, e.g. VMS Pascal and VMS BASIC.

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fanf2 1064 days ago
BLISS is a typeless word-oriented language like BCPL, so I am surprised to see it in this list. Also I am amused to hear VAX/VMS described as a mainframe operating system.
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pjmlp 1064 days ago
Well, it had bounds checking.

I always call them mainframes, regardless if the name is micro or whatever is the pedantic nomenclature.

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