Comment by vasco
2 years ago
That's a huge instance with an enterprise license on top. Most large SaaS companies can run off of $5k / m or cheaper RDS deployments which isn't enough to pay someone. The amount of people running half a million a year RDS bills might not be that large. For most people RDS is worth it as soon as you have backup requirements and would have to implement them yourself.
> Most large SaaS companies can run off of $5k / m or cheaper RDS
Hard disagree. An r6i.12xl Multi-AZ with 7500 IOPS / 500 GiB io1 books at $10K/month on its own. Add a read replica, even Single-AZ at a smaller size, and you’re half that again. And this is without the infra required to run a load balancer / connection pooler.
I don’t know what your definition of “large” is, but the described would be adequate at best at the ~100K QPS level.
RDS is expensive as hell, because they know most people don’t want to take the time to read docs and understand how to implement a solid backup strategy. That, and they’ve somehow convinced everyone that you don’t have to tune RDS.
If you're not using GP3 storage that provides 12K minimum IOPS without requiring provisioned IOPS for >400GB storage, as well as 4 volume striping, then you're overpaying.
If you don't have a reserved instance, then you're giving up potentially a 50% discount on on-demand pricing.
An r6i.12xl is a huge instance.
There are other equivalents in the range of instances available (and you can change them as required, with downtime).
> GP3... as well as 4 volume striping
For MySQL and Postgres, RDS stripes across four volumes once you hit 400 GiB. Doesn't matter the type.
The latency variation on gp3 is abysmal [0], and the average [1] isn't great either. It's probably fine if you have low demands, or if your working set fits into memory and you can risk the performance hit when you get an uncached query.
12K IOPS sounds nice until you add latency into it. If you have 2 msec latency, then (ignoring various other overheads, and kernel or EBS command merging) the maximum a single thread can accomplish in one second is (1000 msec / 1 sec / 2 msec) = 500 I/O. Depending on your needs that may be fine, of course.
> If you don't have a reserved instance, then you're giving up potentially a 50% discount on on-demand pricing.
True, of course. Large customers also don't pay retail.
> An r6i.12xl is a huge instance.
I mean, it goes well past that to .32xl, so I wouldn't say it's huge. I work with DBs with 1 TiB of RAM, and I'm positive there are people here who think those are toys. The original comment I replied to said, "large SaaS," and a .12xl, as I said, would be roughly adequate for ~100K QPS, assuming no absurdly bad queries.
[0]: https://www.percona.com/blog/performance-of-various-ebs-stor...
[1]: https://silashansen.medium.com/looking-into-the-new-ebs-gp3-...
Definitely--I recommend this after you've reached the point where you're writing huge checks to AWS. Maybe this is just assumed but I've never seen anyone else add that nuance to the "just use RDS" advice. It's always just "RDS is worth it" full stop, as in this article.
To some extend that is probably true, because when you’ve built a business that needs a 500k/year database fully on RDS it’s already priced into your profits, and switching to a self-hosted database will seem unacceptably risky for something that works just fine.
> it’s already priced into your profits
Assuming you have any. You might not, because of AWS.
I mean, just use supabase instead. So much easier than RDS. Why even deal with AWS directly? Might as well have a Colo if you need AWS.
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>Most large SaaS companies can run off of $5k / m or cheaper RDS deployments which isn't enough to pay someone.
After initial setup, managing equivalent of $5k/m RDS is not full time job. If you add to this, that wages differ a lot around the world, $5k can take you very, very far in terms of paying someone.