> Motherboards, CPUs, RAM chips, GPUs are analog and physical objects. For AWS to switch a DC from one mobo to another just to find out that this one draws 5% m

> Motherboards, CPUs, RAM chips, GPUs are analog and physical objects. For AWS to switch a DC from one mobo to another just to find out that this one draws 5% more power and their standard backup generator can't handle it, which now starts a chain reaction of upgrades is going to incur real world costs. Costs that can't be amortized by writing some code to make the motherboards look the same. Being physical isn't different. The data center is designed to allow systems that consume up to, for example, 500W. When one consumes 400W and another consumes 420W, they're still fungible. A system that consumes 525W can't be used, but you know that so you don't use those. > This is basically the A/B testing/one-armed bandit problem. How much do you spend time exploring alternatives vs how much time to you reap the benefits of the fact that all your hardware is exactly the same and best of breed, as based on your testing? That isn't the relevant problem. Even if you choose monoculture, you still have to pay the cost of weighing your alternatives to decide which single model to use. The cost of diversity is that the second best model on some metric is 20% worse than the best. But that is also the advantage, because on some other metric it's 20% better. You can use each model for its strength. And since you can't perfectly predict the future, when something unexpected happens you're better able to handle it, because for any given thing that only some systems can do, you will have some systems that can do it. > These situations simply don't lose enough money to make up for the gains of a monoculture. Beware survivorship bias. It's easier to find an active monoculture company that has never had a major problem than one that has, because having a major problem in a monoculture often results in bankruptcy. > Do you/they use five different cloud providers in equal measure to make sure you have diversity if one has an issue? For services with high availability requirements, people absolutely do that. > Do you/they use five different software stacks in case there is a remote exploit for RoR and PHP holds things up? That wouldn't reduce attack surface. The relevant thing people do is to use two factor authentication. > Do you/they buy groceries at five different grocery stores in case one of them has an e. coli outbreak that the other four don't? Having multiple local grocery stores is a thing people want. And people do actually use them, because different stores have the best price or quality for different products. > chances are you've at some point built a RAID array. Did you put different size and performance drives from different manufacturers into it or did you buy N of the same drive type to ensure even performance? If so, why? These are spec differences, not supplier differences. There is no issue with using drives of the same size and speed from different manufacturers. Also compare ZFS, which allows you to efficiently use unmatched drives for the same filesystem.