I can think of a few good reasons. Strategic (you don’t want to hand over to a foreign power your critical infrastructures). Diversification (if all your banks run on aws, the day aws goes down you don’t have a banking system anymore). Not being at the mercy of a capricious tech billionaire (what happened to Parler could very well happen to a state if the said billionaire doesn’t like your policy).

I’m unaware of any Core Banking Systems (CBS) that runs on a cloud provider with the exception being Finastra (Azure). Other parts of retail banking stacks? Sure. Not their cores.

Thought Machine’s Vault targets the big 3 IIRC.

The major cloud providers all aim for 99.999% uptime. Keep in mind that 99.99% uptime means ~4 minutes of downtime a month. I think there are other reasons that banks may not want or have the ability to run their core services on the cloud.

The vast majority of retail banking institutions do not run their core. They outsource it to the major core vendors to ‘protect themselves from themselves’.

It’s atypical motivation but one of the few verticals I know of where the cloud is largely out of the equation.

Let's be honest, it's Azure. The only reason you choose it is because either you compete with Amazon in some way, or you hate your infrastructure engineers, or don't know better.

Or because you already use Microsoft mail, so you already have Azure AD there, and they sent you some credits in an email, and then...

I think Azure is cheaper for certain workloads as well, and at one point had DCs in places where AWS didn't. But it's mostly the "we already buy X Microsoft product, and they cost about the same, so..."

Quite a few businesses are still simply more comfortable with any idea if Microsoft does it than otherwise.

From what I’ve seen up until now it’s often the last option. I’ve seen comparisons between the major cloud providers, but those have often been on the level of “I can boot a VM with x cpu on provider y and z”. With these kind of comparisons a major deciding factor then is discounts. And that’s an area Microsoft excels at.

Aim.. Google for sure doesn’t come close to this for uptime. Microsoft as well.

Despite what their status pages would have you believe ;)

If that's what they're aiming for they're sure missing their targets an awful lot. I guess that I'm proud that they're aiming for the stars!

The comment you're replying to says the cloud should be used as a redundant system. So they are inherently saying they are not immune to outages.

Your comment is a fine example of the standard rhetoric from the 'move everything to the cloud' marketing people, but perhaps organizations should consider that they don't have to go with one cloud provider as a single point of failure. It's the lazy way of abstracting away responsibility and blame to some other party, and in my experience often does not result in better availability than a properly implemented "belt and suspenders" approach.

There’s a complexity cost, though, right? It’s not free to run two different systems, manage two different billing systems, different tools, pay for cross-provider bandwidth, etc.?

I’m sure there are some cases where the cost is worth the complexity, but I don’t think it’s cut and dried as written here. Most cloud providers are very reliable, and my guess is that you are more likely to have a self-inflicted outage due to the complexity of your infrastructure than the cloud provider having an outage.

Or it’s borne of experience of doing it oneself being much less reliable than cloud providers even accounting for these rare outages.

On the evidence, yes. Cloud providers frequently have outages lasting multiple hours affecting millions of clients. Some governments manage to run critical servers without downtime.

While I accept of course that there are government-owned systems that have uptime measured in years (decades?), I think that extrapolating that into an argument about the overall reliability of those systems falls into survivorship bias.

But if I had to make an a priori prediction about which systems would have the better reliability over the long term - cloud-based or those run out of a corporate DC - my money would be on the cloud-based systems.

The cloud providers are going to have better management of power/network/hardware than the most mature government agency, simply because it's a core capability for them.

Change is a leading cause of outages. The cloud providers are constantly changing and upgrading their services, and constantly have downtime ranging from minutes to hours.

In contrast UK gov servers like hmrc.gov.uk (for example) are pretty stable, I can't remember the last time I heard about an outage.

Cloud providers are certainly better at some things (like staying up to date with latest tech), but I'd contend reliability is not one of those things based on their prominent and frequent outages (at least several a year).

I’m starting to think the answer is yes. My small systems have not had outages like Azure has.