Not to detract from this article explicitly on the subject of AWS, but ... if you are relying on any single cloud provider then you are probably not going to scale beyond a certain point, since it means that reliability (ie. heterogeneity - re: cloud providers, physical/logical points of presence, legal jurisdictions, etc.) is not all that important to you. At a certain point, a cloud provider neutral approach is called for.
Once you have two providers, you are forced to only use the features offered by each of them and use an abstract layer (API agnostic dev).
Abstraction layers don't necessarily need to produce lowest common denominator results.
Plus, AWS offers a wide range of strategies to ensure the availability of its infrastructure (Availability Zone, Regions, CDN etc.)
You still wind up vulnerable to quirks of the single provider though! For example, account freeze for whatever reason (financial quirks, legal issues, regulatory change) any multi-site failures (eg. financial, operational, legal, security) at that provider.
> Abstraction layers don't necessarily need to produce lowest common denominator results.
Except in the special case that you can build the functionality not provided by using other functionality that is, I think they do, since otherwise it's leaking. A leaky abstraction is often worse than none.
I think your assumption is that cloud providers with different features cannot be abstracted without making the whole abstraction 'leaky'.
While your perspective may hold for a traditional, rigid, single-layer, abstraction layer with the most simplistic, binary-level feature presence, it does not hold for better formed solutions. From https://en.wikipedia.org/wiki/Abstraction_layer: All problems in computer science can be solved by another level of indirection (David Wheeler).
Some real world differences between cloud providers: available hardware, available installation images (OS images), available bandwidth, available logical location on the internet, available physical location (legal jurisdiction, etc.), scale-out time, cost model.
How do you conceive of these differences, and then deploy arbitrary services to an arbitrary number of individual instances running unique combinations of cloud provider specific features on unique cloud-provider deployed OS images in parallel? There are various approaches, but it's not that hard to come up with a functional set of abstractions. Think about it.
I'd like to hear more about this. When buying or renting physical machines is worthwhile, how would I actually go about it? Should I get them preassemblied, should I buy parts and then glue it together, or people just generally rent their infrastructure?
If your workload is totally standard then renting dedicated servers can make sense, it's certainly flexible if you expect to scale on a monthly basis. However, if you need something "premium" like an SSD or lots of RAM then you can end up paying $300/month. Buying a used server off eBay for $400, putting a new HDD in it, and getting a colocation for $100/month will be the most cost-efficient for those on a tight budget. The provider will usually do basic maintainance like replacing HDDs for a small fee.
That said, if money is not a problem then go with whatever lets you get stuff done with the least pain.
at a certain point, real hardware is called for, if you wish to scale. my experience: 1/3 the price, 2x the performance in softlayer vs a $97k/mo ec2 spend. Obviously specific to my workload, but you should at least benchmark on real hardware.
However, cloud does have benefits that you lose with physical, eg. speed of initial deployment, speed of scale-out (no ordering/assembly/wiring/burn-in test/etc. lead times), maintenance and data center proximity issues (often translating to increased costs), masking of some of the legal/financial issues of multi-site presence (eg. if you want multi-jurisdictional points of presence), etc.
There are of course ways to use mixed strategies to combine cloud/third party services/CDN with physical infrastructure.
As always, "right tool for the job". I just felt it was worth mentioning there are limitations with single-provider cloud infrastructures as it's possible to get excited about the benefits of a particular approach without considering the full picture.
