>Far be it from me to tell anyone how to write software, but why build a database on top of S3 when you can just chuck the metadata into RDS with however much replication you want?
Cost and reliability?
* Using S3 as a simple database is generally going to be much cheaper than RDS.
* If you turn on point in time restore, then losing data stored in S3 is not a possibility worth worrying about on a practical level for most people. RDS replication is easy enough to use, but adds more cost and a little bit of extra infra complexity.
That sort of logic doesn't really apply here because:
* RDS costs obviously scale linearly with ongoing time and probably scale linearly with the total amount of data being backed up. So depending on the revenue of the business, these extra costs could easily end up outweighing the (notional) cost of the time saved, which is mostly a one-off expense.
* The cost of a software engineer's time is notional in the context of a one-person business. The author of Tarsnap isn't going to be able to employ fewer than zero additional software engineers to maintain Tarsnap because of the time saved by using RDS.
> I realized that this was
introduced by some code I wrote in 2014: Occasionally Tarsnap users need to
move a machine between accounts,
with an implicit "and I fixed that code now" or "and I will fix that tomorrow when I get enough sleep". Let's hope he writes later a follow up explaining the details.
> [a] postmortem on the front page of HN
Is that bad? I upvoted this almost instantly, then went to the comment section to upvote cperciva if he was here, then I read the full post and verified my first upvote was correct.
But more than that: servers should be stateless! A server going down should never take down your business.
If you use Postgres, and stateless servers, then if a server goes down it's no problem, it gets rebooted and there may be other servers and a load balancer to pick up the load. If Postgres goes down, you have a replica, or it gets rebooted, and Postgres always recovers from crashes (in my experience), and if it doesn't you have PITR.
AWS has everything under the sun to prevent this kind of thing happening. This is a 1990's outage. This didn't have to happen.
The hardware failure was on the server running the application code, so RDS replication wouldn’t have helped. You’re right of course that this failure points to a lack of redundancy – but that’s a separate issue from choosing S3 vs. RDS as the data layer.
By the way, S3 is insanely reliable and in fact more reliable than a replicated RDS setup. So switching from S3 to RDS would almost certainly reduce the basic reliability of the data layer, however many conveniences it might bring.
PostgreSQL and RDS are quite a bit more than just a log-structured data store, and are not prima facie the correct solution for this problem domain, regardless of how much arrogant ignorance you bring to bear on the debate.
You broke the site guidelines badly in more than one place in this thread. I realize you're trying to defend someone's work against what you feel is unfair criticism, but breaking the site guidelines yourself, with swipes and name-calling and flamewar, is exactly the wrong way to do this.
Would you please stop posting flamewar comments and breaking the site guidelines? You've been doing that repeatedly and badly in this thread. We end up having to ban such accounts, and I don't want to ban you.
Fortunately it doesn't look from your recent comments that you've been in the habit of posting this way, so it should be easy to fix.
Just … stop. This is the first outage in 11 years.
You’re being unnecessarily arrogant and antagonistic up and down this thread
You’re not smarter than everyone else here, you don’t have better or more perfect knowledge, and you almost certainly wouldn’t have built a better or more reliable system.
Cost and reliability?
* Using S3 as a simple database is generally going to be much cheaper than RDS.
* If you turn on point in time restore, then losing data stored in S3 is not a possibility worth worrying about on a practical level for most people. RDS replication is easy enough to use, but adds more cost and a little bit of extra infra complexity.