[HN Gopher] Tolerating full cloud outages with Monzo Stand-in
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       Tolerating full cloud outages with Monzo Stand-in
        
       Author : abritishguy
       Score  : 47 points
       Date   : 2025-02-13 18:23 UTC (4 hours ago)
        
 (HTM) web link (monzo.com)
 (TXT) w3m dump (monzo.com)
        
       | noodlesUK wrote:
       | This seems especially relevant given the massive outage that
       | Barclays, another major UK bank just suffered. Barclays was down
       | for around two days with customers unable to spend money at all.
       | 
       | I suppose had they implemented a similar system, they would have
       | degraded into a minimum viable banking system rather than the
       | total outage that impacted so many brits.
        
         | mmikeff wrote:
         | On the last day that tax payments were due
        
       | QuinnyPig wrote:
       | What I wonder is "have they isolated third party dependencies?"
       | If AWS is hard down, those may well be impacted--in some cases,
       | by their own third party dependencies. You can test turning off
       | your AWS environment, but you can't really test turning off S3
       | for everyone...
        
         | sleepgou wrote:
         | From what I understand of payment systems this is so that
         | payments through card machines, contactless payments for public
         | transport, cash withdrawals from ATMs, etc. all continue to
         | work. A lot of those systems are surprisingly insulated from
         | AWS simply by virtue of being extremely archaic
        
           | fujinghg wrote:
           | I wouldn't assume that is the case. The failure modes are
           | different that is all.
           | 
           | I saw a whole corp POS platform a couple of decades ago that
           | was hanging off a TFTP server on a machine that no one dared
           | turn off in case the world ended. One day the DC UPS failed,
           | it didn't come back up and they had no retail operations for
           | several hours while they sent a bunch of cash to a guy who
           | had left to help them fix it.
           | 
           | There's stuff like that everywhere lurking in the archaic.
           | 
           | I know of a modem in a DC which is used to talk to a branch
           | office running AS400 hardware that is so old they have to buy
           | spares off eBay.
        
       | theginger wrote:
       | A decent setup which allows you to prove you are not dependent on
       | 1 cloud provider will probably pay for itself when it's time to
       | negotiate discounts.
        
         | cbg0 wrote:
         | I doubt the sales folks you'll be talking to will care about
         | your multi cloud deployment, as they don't have the skills to
         | verify something like that.
        
       | Koffiepoeder wrote:
       | Unrelated tangent: I was reading the article and suddenly
       | realised that I could not identify the font. After a quick
       | search:
       | 
       | > Our functional typeface is Monzo Sans, a custom cut of
       | Universal Sans, meaning it's unique to Monzo. We chose it for
       | maximum readability, with generous dots and curled ends.
       | 
       | Intersting choice, but I dig it :)
        
       | tikkabhuna wrote:
       | These blog posts are why I continue to support Monzo. Their
       | openness is really appreciated.
        
       | joshstrange wrote:
       | Completely unrelated to this blog post but I really dislike
       | Fintech saying "Get paid early" in their promos.
       | 
       | It's clearly marketing at someone too stupid to be able to see
       | right through how utterly useless that is. If you are celebrating
       | getting your paycheck 1 day earlier (every time) then your
       | financial literally and financial health are probably in the
       | toilet. They _must_ know they are preying on people with
       | statements like that.
       | 
       | Then again, 90% of Fintech seems to be just a heavy layer of
       | lipstick over an archaic system. Often with very little care of
       | if any of the tools actually help people and more of a focus on
       | how flashy or how much people _think_ they are being helped.
        
         | jkingsman wrote:
         | Though, in some cases (like when it's your bank saying it),
         | it's usually just them frontrunning reliable (coming from a
         | payroll provider) and predictable (getting paid the same time
         | each month) ACH transactions with a near-zero likelihood of not
         | settling, then crediting you the money before the ACH is
         | totally settled, so not ALL cases are fintech gimmicks.
         | 
         | But most are, and unfortunately, as the proliferation of payday
         | loans shows us, there is no shortage of desperate people and
         | organizations willing to take advantage of that.
        
           | joshstrange wrote:
           | > not ALL cases are fintech gimmicks.
           | 
           | Fair and that's all well and good. I'm just saying if 1-3
           | days delay of getting your paycheck is going to have a big
           | impact on one's life then I encourage one to reexamine their
           | decisions, something else is the problem.
        
           | blibble wrote:
           | as a banker, when I first heard about that I did I wonder if
           | they've modeled that risk correctly
           | 
           | it's the sort of thing that could probably wipe out their
           | capital completely in a black swan event
        
             | simonvc wrote:
             | It's a risk that was very much understood and it's fully
             | covered.
        
               | blibble wrote:
               | I've heard that one before
        
             | quesera wrote:
             | There's an ocean of historical data to predict reversal or
             | settlement failure of ACH transactions.
             | 
             | I would guess that payroll credits are the second most-
             | reliable category in the ocean of ACH transactions, right
             | after US Treasury payments.
             | 
             | How black would this swan need to be to blow up this
             | stability?
        
               | blibble wrote:
               | not sure what american payment transfers have to do with
               | UK BACS payments, but ok
               | 
               | > I would guess that payroll credits are the second most-
               | reliable category in the ocean of ACH transactions, right
               | after US Treasury payments.
               | 
               | maybe some sort of lunatic getting control of the US
               | treasury payment systems?
               | 
               | I suppose that can't ever happen
        
           | quesera wrote:
           | Right, some banks will not post a deposit to your account
           | until after a holding period. I deal with a lot of ACH
           | payments, and despite a very strict schedule in the network,
           | the retail customer-facing side is surprisingly
           | unpredictable.
           | 
           | So the "post credit early" promise is not a gimmick, but the
           | whole idea of being paid early _is_ a gimmick. The next pay
           | period is still a full period away, so any benefit to being
           | credited early is literally a one-time, and probably just
           | one-day thing.
        
           | andrewaylett wrote:
           | Remember that Monzo is a UK institution -- ACH isn't
           | relevant, and they _can_ see the payment in flight if it 's
           | using BACS.
           | 
           | https://monzo.com/blog/2019/08/20/monzo-now-lets-you-get-
           | pai...
        
       | 4ndrewl wrote:
       | Really interesting. Would love to understand how they came to the
       | decision to build this,and whether there's any precedent for it.
        
         | quesera wrote:
         | Payment card networks have delegated authorization plans, where
         | if a major processor goes down, they will still route
         | transactions and use a simplified secondary network for making
         | approval decisions.
         | 
         | It's called "stand-in processing", and I assume it's the
         | inspiration here.
        
           | 4ndrewl wrote:
           | The Monzo example feels different though, as they're
           | explicitly not looking to replicate all functionality, just
           | something minimal to get by whilst they fix the primary cloud
           | services.
        
       | paulbjensen wrote:
       | My only conclusion is that Monzo would rather embrace the
       | apocalypse than rely on Microsoft Azure to provide a tertiary
       | fallback.
        
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       (page generated 2025-02-13 23:00 UTC)