They run 2 Outlook instances. For redundancy. /s
How NASA built Artemis II’s fault-tolerant computer
81–90 of 257 posts
Re: How NASA built Artemis II’s fault-tolerant computer
#82Earlier quoted context omitted.
Wow. What a hand wave away of the intrinsic challenge of writing fault tolerant distributed systems. It only seems easy because of decades of research and tools built since Google did it, but by no means was it something you could trivially add to a project as you can today.
> fault tolerant distributed systems I mean there were mainframes which could be described as that. IBM just fixed it in hardware instead of software so its not like it was an unknown field.
Even if that were actually true (it’s not in important ways) Google showed you could do this cheaply in software instead of expensive in hardware.
You’re still hand waving away things like inventing a way to make map/reduce fault tolerant and automatic partitioning of data and automatic scheduling which didn’t exist before and made map/reduce accessible - mainframes weren’t doing this.
They pioneered how you durably store data on a bunch of commodity hardware through GFS - others were not doing this. And they showed how to do distributed systems at a scale not seen before because the field had bottlenecked on however big you could make a mainframe.
Re: How NASA built Artemis II’s fault-tolerant computer
#83The quote from the CMU guy about modern Agile and DevOps approaches challenging architectural discipline is a nice way of saying most of us have completely forgotten how to build deterministic systems. Time-triggered Ethernet with strict frame scheduling feels like it's from a parallel universe compared to how we ship software now.
Agile is not meant to make solid, robust products. It’s so you can make product fragments/iterations quickly, with okay quality and out to the customer asap to maximize profits.
The manifesto refers to “working software”. It does not say anything about “okay quality”.
Re: How NASA built Artemis II’s fault-tolerant computer
#84Earlier quoted context omitted.
What happens when they don't?
If you have a point to make, make it.
What my question is hinting at is that there's actually some really interesting engineering around resolving what happens when the systems disagree. Things like Paxos and Raft help make this much more tractable for mere mortals (like myself); the logic and reasoning behind them are cool and interesting.
Re: How NASA built Artemis II’s fault-tolerant computer
#85The quote from the CMU guy about modern Agile and DevOps approaches challenging architectural discipline is a nice way of saying most of us have completely forgotten how to build deterministic systems. Time-triggered Ethernet with strict frame scheduling feels like it's from a parallel universe compared to how we ship software now.
It's not like the approach they took is any different. Just slapped 8x the number of computers on it for calculating the same thing and wait to see if they disagree. Not the pinnacle of engineering. The equivalent of throwing money at the problem.
>Just slapped 8x the number of computers on it
‘Just’ is not an appropriate word in this context. Much of the article is about the difficulty of synchronization, recovery from faults, and about the redundant backup and recovery systems
Re: How NASA built Artemis II’s fault-tolerant computer
#86Earlier quoted context omitted.
“Agile” doesn’t mean that you release the first iteration, it’s just a methodology that emphasizes short iteration loops. You can definitely develop reliable real-time systems with Agile.
> “Agile” doesn’t mean that you release the first iteration Someone needs to inform the management of the last three companies I worked for about this.
Management understand it less than anyone else does.
Re: How NASA built Artemis II’s fault-tolerant computer
#87Earlier quoted context omitted.
If you have a point to make, make it.
What my question is hinting at is that there's actually some really interesting engineering around resolving what happens when the systems disagree. Things like Paxos and Raft help make this much more tractable for mere mortals (like myself); the logic and reasoning behind them are cool and interesting.
[flagged]
Re: How NASA built Artemis II’s fault-tolerant computer
#88Earlier quoted context omitted.
Agile is not meant to make solid, robust products. It’s so you can make product fragments/iterations quickly, with okay quality and out to the customer asap to maximize profits.
“Agile” doesn’t mean that you release the first iteration, it’s just a methodology that emphasizes short iteration loops. You can definitely develop reliable real-time systems with Agile.
I would differentiate between iterative development and incremental development.
Incremental development is like panting a picture line by line like a printer where you add new pieces to the final result without affecting old pieces.
Iterative is where you do the big brush strokes first and then add more and more detail dependent on what to learn from each previous brush strokes. You can also stop at any time when you think that the final result is good enough.
If you are making a new type of system and don’t know what issues will come up and what customers will value (highly complex environment) iterative is the thing to do.
But if you have a very predictable environment and you are implementing a standard or a very well specified system (van be highly complicated yet not very complex), you might as will do incremental development.
Roughly speaking though as there is of course no perfect specification which is not the final implementation so there are always learnings so there is always some iterative parts of it.
Re: How NASA built Artemis II’s fault-tolerant computer
#89Earlier quoted context omitted.
I take the opposite message from that line - out of touch teams working on something so over budget and so overdue, and so bureaucratic, and with such an insanely poor history of success, and they talk as if they have cured cancer. This is the equivalent of Altavista touting how amazing their custom server racks are when Google just starts up on a rack of naked motherboards and eats their lunch and then the world. Le…
Modern software development is a fucking joke. I’m sorry if that offends you. Somehow despite Moore’s law, the industry has figured out how to actually regress on quality.
And overall performance in terms of visible UX.
Re: How NASA built Artemis II’s fault-tolerant computer
#90Earlier quoted context omitted.
I take the opposite message from that line - out of touch teams working on something so over budget and so overdue, and so bureaucratic, and with such an insanely poor history of success, and they talk as if they have cured cancer. This is the equivalent of Altavista touting how amazing their custom server racks are when Google just starts up on a rack of naked motherboards and eats their lunch and then the world. Le…
> ...they talk as if they have cured cancer. I'd chalk that up to the author of the article writing for a relatively nontechnical audience and asking for quotes at that level.
So the quote is right somewhat, right?
If you are writing to non technical people and you use such high wording.