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Discussion (12 Comments)Read Original on HackerNews
I've been doing reliability for most of my career, and have always been able to hide behind, "We're not a bank, if we lose a few requests it doesn't matter". They can't do that. :)
One advantage that they have is that the market closes, so they can do maintenance that takes the whole system down, but when you're running a global consumer product, it's a lot harder to do that without pushback.
So for most of us, our stress is around zero downtime maintenance, and theirs is around never dropping a request when the system is live.
There are multiple layers of controls and manual interventions and things, which while absolutely painful, slow, expensive and shitstorm-conjuring -- are ultimately the final authority on some failures.
For e.g, in payments -- every single settlement or clearing anomaly is looked at by a real human, and rectified/rebooked manually.
So, yeah, the stakes can be really high when you have a couple billion in memory on your server, but -- it's just a system.
And it will fail, and we plan for it to do so.
I've always said that with infinite money we could get 100% uptime, but no one has infinite money. Trading firms are about as close as I can imagine to infinite money though.
I work with a major one and, being honest, from day one it was obvious they were incompetent. They employ a huge number of engineers and are unable to deliver basic features at any reasonable pace. Not even remotely close to it either (as in: you ask them to do something, they say yes, execs say yes, you get a deadline, date comes...deployment difficulties, environment not working, run around goes on and on forever).
I remember the CEO got on a call with us at the start and was slapping himself on the back saying they had no downtime...because they were able to do maintenance when markets shut (and have heard very bad things about how that goes). But it is 24/7 world now, our service is up 24/7 and, of course, this led to massive issues in time due to the very different expectations around delivery/quality. Our execs were impressed, our engineers said this was a bad sign. And, ofc, it transpired that they were total amateurs (to be clear, this is one of the biggest exchanges in the world) and were unable to deliver.
To come back to my original statement: there is a company of 16 people total who is, from the point of view of customers, delivering features faster. It is difficult to understate how insane that is.
If done right, it would be a complete separate system. Separate IP addresses and all.
Isn't the plan more like 23/5 like is already the case for several markets?
I can't see the standard sessions moving more 9:30am/4pm weekdays to 24/7. I take it they'd still let, at least, one hour off for technical reasons.
If I'm not mistaken it's the reason several markets are 23/5 and not 24/5: that one hour of downtime is basically for servers/maintenance right? (maybe someone can chime in)
P.S: I take it technically there's 24/7 trading already seen that cryptocurrencies exchanges are opened 24/7 (I'm not sure: but I think that's the case) but I don't think those do anywhere near the volume of, say, options trading on equities during standard sessions (40 Gbit/s with peak over 70 Gbit/s for the full options feed).
Every so often a new stock is listed or a stock ticker is changed or a stock is split, etc. There are smaller changes every single day, like to the settlement date of your trade.
It's very convenient to be able to restart all your systems at 5pm, have them all load the updated reference data, and start them again in time for 6pm (or 7pm, or 4am tomorrow...). Even if you trade stocks and options and currencies and futures all over the world, a quirk of the calendar means they're basically all closed between 4 and 5pm Chicago time.
Of course it's possible in principle to build systems where all this is dynamic and you can seamlessly trade with the old configuration at 4:59:59.999 and start trading the new one a millisecond later. But literally everyone has built systems that don't work on this, that rely on being able to chunk the continuous passage of time into discrete days. It would be painful to rearchitect them all now.