11 9s of durability is about the likelyhood of AWS loosing your data. It doesn't cover the likelyhood of you being able to access your data that's called availability.

For example on GCS (Google's S3)...A storage class specifies how many locations the data is made available. All storage classes share the same durability (chance of google loosing your data) of 99.999999999%, but have different availability (chance of being able to retrieve data).

> chance of google not loosing your data of 99.999999999%

git commit -m 'typo'

I think it's a little better than that, actually.

It says that their ideal-case failure rate is 11 nines; that's how much you should lose to known, lasting issues like machines failing and cutting over.

Amazon's actual SLA offers 2 nines and 3 nines as the credit thresholds. So they're stating the reliability of their known system, and the rest is for events like this.

Durability and uptime are not the same thing. Durability is about the chance of losing your data and has nothing to do with service disruptions. Their uptime SLA is much lower. Looking at [1], it looks like the SLA says 3 9s (discounts given for anything lower) of uptime.

[1] https://aws.amazon.com/s3/sla/