> I think it's very hard to run a service by yourself of this magnitude reliably, but I'd always take a 99.9% availability daily backup service that runs right at SLO over one that's down for a day once in a blue moon.
That's a fallacy right there. Your assumption should be that any service you rely on will be down once in a blue moon, and possibly for a day or even longer.
> Also, parent is talking about ingestion. If your backups aren't configured well and the backup process fails, then your backup may not end up durable.
Yes, indeed, you need to do your work and you don't get to point at others for not doing it right.
> I also don't think your definition of reliable is generally recognized, which I'd generally call durability.
Reliability, durability and availability are all industry terms and have very clear definitions. These are not the same definitions that you would use in ordinary conversation with laypeople but when we're talking shop those are definitely allowed.
> I wouldn't say the scenario above is a durability failure, but an example of the consequences of poor availability.
No, it is a consequence of poor engineering on the part of the user of the service, and is a completely different issue. You engineer your service to ensure that your assumptions hold true and if you fail at doing that your service will fail. When is then only a matter of time and combination of circumstances, but fail it will.
