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Monzo Stand-In

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Re: Monzo Stand-In

#21

Post by danpalmer »

YawningAngel wrote: post #16
danpalmer wrote: post #7

I can't help but think this isn't the best idea, it raises so many questions. How does fail over work (it failed for me!), can you safely fail over, how does product think about the stack, is it funded well enough, how do you scale a system from zero to all traffic instantly, how do you effectively keep this environment warm, how do you determine which services are critical enough to be in it, how do you manage findi…

I'm a bit curious about Spanner. At $EMPLOYER we were going to do multi cloud with multi-region CockroachDB clusters but gave up on it because write latencies and costs were too high. Do you not get the same thing with Spanner, where technically you can have multi region but it's very unattractive to actually do?

I'm afraid I'd have to defer to the public docs on this. I've only used it internally and a bunch of that is not public.

What I would say is that it's considered to be much better than CockroachDB, but that there's no getting around physics. Spanner is subject to the same speed of light... but in every other way it does what it can do to improve things at every level. Google's use of GPS hardware for better timing is public.

Re: Monzo Stand-In

#22

Post by ricardobayes »

danpalmer wrote: post #12
ricardobayes wrote: post #11

Earlier quoted context omitted.

No, it's a great idea. Any systems engineer knows redundancy is good, even better if it's across providers. I see no issues with this from a system architecture point of view. As to how the implementation is done that's up to them to do right.

Redundancy is great, absolutely, but there are multiple ways to do it and this is not necessarily the right one. Which is better: 3 DCs for 2 DCs worth of traffic, running the same stack but isolated failure domains... or 4 DCs for 2 DCs worth of traffic, that work in completely different ways, where 2 are left cold until needed. I can see some advantages of the latter, but not a lot. This also isn't about fault tole…

In your Google scope this all works out however if you're a mature but not yet prevalent, neobank whose reputation rides almost solely on availability, I'd still say theirs is a great approach. Even in the unlikely event that AWS throws in the towel and has a hard failure, users can still enjoy a subset of functions without elevated latency. On top of it, it might well be that user data can never leave UK, so geographical redundancy might not even be a thing here.

And yes you are completely right a completely distinct implementation is probably a no-go, but I'd think you could deploy a similar codebase with feature flags, with some frontend differences. I'm speculating but pretty sure they didn't reimplement backend functionality for this.

Re: Monzo Stand-In

#24

Post by varispeed »

> Monzo Stand-in is an independent set of systems that run on Google Cloud Platform (GCP)

Given the US Cloud Act, how Monzo is protecting customers' financial data from being accessed by foreign government without Monzo's knowledge?

Everyone does it, does not excuse it.

Also shows lack of faith in British business.

Re: Monzo Stand-In

#25

Post by sdcfgy »

danpalmer wrote: post #7

I can't help but think this isn't the best idea, it raises so many questions. How does fail over work (it failed for me!), can you safely fail over, how does product think about the stack, is it funded well enough, how do you scale a system from zero to all traffic instantly, how do you effectively keep this environment warm, how do you determine which services are critical enough to be in it, how do you manage findi…

I suspect Monzo was bitten by complexity. The network should not be assumed to be reliable and if you make a thousand things (microservices) with network between them regardless of what you think may happen, it’s entirely impossible to test it with any level of certainty. And that’s worse if you have a complete failover scenario.

Add the instability of the average cloud control plane during an outage and things get rather nasty rather quickly in reality. We’ve been through that with AWS’ numerous outages.

My company is victim of this mindset. We sacrificed tested and assured reliability on physical hardware in multiple redundant data centres for cloud and microservices. Mostly driven by Monzo’s claims, semi religious thinking and me too.

Reliability is measurably down, cost is higher, latency is higher and we cannot fail over to another provider because someone went to an AWS conference and started using all the toys. Even if we did get rid of those dependencies, during an outage the kubernetes control plane is so tied into the vendor that we’d be fucked anyway. Last time the ingress controller couldn’t change ALBs for example.

Only winner here is Bezos and the decision makers CVs. The losers are the customers. We live in the stupidest of times.

Re: Monzo Stand-In

#26

Post by IshKebab »

danpalmer wrote: post #13
IshKebab wrote: post #10

Monzo is great. Rare example of a consumer banking company that makes things easy. I just signed up for their phone service in literally 3 minutes. Didn't even need to talk to anyone to port my old number. I'm going to move all my ISAs and SIPP to them next I think.

> Didn't even need to talk to anyone to port my old number That seems like pretty low stakes – I wouldn't expect to talk to anyone to sign up and transfer to a consumer service in the UK. I don't think I've spoken to anyone for something like this in the last 10 years or so.

Well I haven't moved my number for a couple of decades at least, but the last time I did you had to phone them and go through the whole "are you sure? Let me see if I can get you a better deal" nonsense.

Re: Monzo Stand-In

#27

Post by IshKebab »

broadben12 wrote: post #14
IshKebab wrote: post #10

Monzo is great. Rare example of a consumer banking company that makes things easy. I just signed up for their phone service in literally 3 minutes. Didn't even need to talk to anyone to port my old number. I'm going to move all my ISAs and SIPP to them next I think.

This is either a bot comment, or you have a very poor understanding of the UK financial market. They are quite far down the leaderboard for ISA rates and SIPPs.

I don't think they actually are. Platform fees are capped at £250 and their default managed fund fees is 0.14% which is pretty normal. Also I deliberately want a platform that doesn't allow trading individual shares because otherwise I have to report those to my employer every quarter and I can't be bothered with that admin.

Re: Monzo Stand-In

#28

Post by greatgib »

There are 3 things I have in mind when reading this:

- it should be so frustrating for a dev to work on a full core banking that is mostly useless and userless except maybe 1h every 3 years.

- if you build a totally different implementation to handle high traffic transaction from third parties that don't operate for days or months, i would expect it to be fragile. Like for example suddenly you receive unicode special chars that you didn't expect in labels and boom.

- last, I think that in most incident cases, the situation is not clear enough to be able to switch to the full different system. Rarely it will be your whole infra but part of it, so there is always the question to what to do in such a case, or if your main infra goes crazy with loops for example, or if you lose control because of a network, aws, infrastructure issue thr problem might be that you have no visibility on what is working and what is not, not necessarily the control to stop the faulty services, etc...

Re: Monzo Stand-In

#29

Post by danpalmer »

IshKebab wrote: post #26
danpalmer wrote: post #13

Earlier quoted context omitted.

> Didn't even need to talk to anyone to port my old number That seems like pretty low stakes – I wouldn't expect to talk to anyone to sign up and transfer to a consumer service in the UK. I don't think I've spoken to anyone for something like this in the last 10 years or so.

Well I haven't moved my number for a couple of decades at least, but the last time I did you had to phone them and go through the whole "are you sure? Let me see if I can get you a better deal" nonsense.

Cancellation is different to porting a number. You'll still need to cancel your previous plan, but legislation fixed carriers holding numbers hostage a while ago.

Re: Monzo Stand-In

#30

Post by barnabee »

danpalmer wrote: post #7

I can't help but think this isn't the best idea, it raises so many questions. How does fail over work (it failed for me!), can you safely fail over, how does product think about the stack, is it funded well enough, how do you scale a system from zero to all traffic instantly, how do you effectively keep this environment warm, how do you determine which services are critical enough to be in it, how do you manage findi…

For truly critical systems and independently developed redundant or backup system that can perform at least the most important functions is clearly superior. Regardless of how much effort goes into making one implementation reliable, there's always the possibility of an issue that takes it out, or forces it to be taken offline.

I don't know how common this is in retail banking but I'm happy to see Monzo do it.

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