The One and the Many

Reflections on moving to the cloud

At $work we recently completed a migration to the cloud. I was a big proponent of doing this. However it wasn't without hiccups. One of the last things we moved made me worry whether the project had been a mistake.

Thinking about this put things in perspective. While not everything is perfect, we gained a lot. I believe the project was the right move.

Here are the pros and cons as I see them.

Con: Performance

This is my major complaint and one I didn't appreciate enough up front.

Going from bare metal to the cloud is a tough pill to swallow in terms of performance. IO in particular is problematic as there is no good solution to having disks as fast as bare metal. On GCP, the best option for fast disks is local SSDs, but they're ephemeral. If you have a workload that can't easily be split horizontally where ephemeral storage isn't a good fit, such as a database server, this is a problem. You're looking at hard options and are bringing yourself closer to an IO wall.

The platforms have an opportunity to improve here, though I understand why it's difficult.

Con: Loss of control

If you integrate with one of the platform's services and it has downtime, there's nothing you can do. That isn't a good feeling when you have customers relying on you.

However cloud or not, you're reliant on others. Even with bare metal you don't control everything.

I don't see this as a negative with the cloud itself. Rather it is a consideration as you integrate with its services to capitalise on its benefits.

Pro: Security

This is the main benefit. I wrote about this topic before, but to list some ways it's a security win:

Yes, "the cloud is other people's servers" and there is nothing magical about it. All of these can be achieved without the cloud, but the question is whether they are feasible.

Pro: Platform services

While I mentioned these as a security tool, platform services are also a benefit in building systems. They solve infrastructure needs that you'd be building, running, and maintaining systems for yourself. A few examples:

I look at such services as high quality, reliable tools that let us focus on the necessarily bespoke parts of our services. Make something the provider's problem instead of yours.

Pro: Infrastructure as code

Concluding thoughts

An interesting question is whether I would advocate for this project again given what I know today.

The main points against are that it was a major investment and that it accelerated hitting difficult performance questions. However the security gains are significant, and security was the primary reason to do it. It's probably the single biggest security gain we could see, and if we hadn't done it, I would see the benefit of it. I believe I would push for it again.

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