5 ms·
It's one of the reasons that silly guarantees like "twelve 9s of reliability" are meaningless. There are humans here. "Accidental human mishap" is gonna happen
by CobrastanJorji 10y ago
It's one of the reasons that silly guarantees like "twelve 9s of reliability" are meaningless. There are humans here. "Accidental human mishap" is gonna happen sometimes, and when it happens it's probably gonna affect a lot of data. Heck, at around 7 or 8 nines you have to account for the possibility that your operations team will decide that all your data is a vicious pack of timberwolves and needs to be defeated.
- pavel_lishin 10y agoAs I understand it, those guarantees don't mean that the service will actually stay up for the given number of 9s; it's that you'll be reimbursed monetarily if and when they go down.
- HeyLaughingBoy 10y agoKinda the same thing, though. I mean, from my perspective there's no substantive difference between me saying "this service will stay up 99.xx% of the time and me buying insurance to pay you for the 0.xx% of the time I might fail. The alternative is that I use the insurance to pay my legal fees when you sue me for not meeting my uptime guarantees.
- jstanley 10y agoIt's not the same thing. The Amazon service might only be costing you $100/mo, but if it goes down the cost to your business might be millions. They'll reimburse you the $100, not the millions.
- SilasX 10y agoI don't think it even means that; their policy says that the reimbursement only happens when your reliability dips all the way down to three 9s: https://aws.amazon.com/s3/sla/ https://aws.amazon.com/s3/sla/
- dkersten 10y agoThe SLA (as you linked) says three nines. The 12 nines quoted by others is durability, not uptime.
- simonebrunozzi 10y agoNote: they say "S3 is DESIGNED for 11 9s of durability". It's PR-speak to say that they don't give you any guarantee, but in theory the system is designed in a magnificent way.
- throwaway4job 10y agoNote they say 'durability' not 'availability'.
- Bartweiss 10y agoI 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.
- cobookman 10y ago11 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).
- dotancohen 10y agoCorrection: 99.999999999% is not the chance of Google loosing your data, it is the chance that Google will cancel any new service or features that you use. See: reader, plus, etc.
- dotancohen 10y agoCorrection: 99.999999999% is not the chance of Google loosing your data, it is the chance that Google will cancel any new service or features that you use. See: reader, plus, etc.
- andrewaylett 10y agoNote that's durability not reliability. You might not be able to get at it with every request (I think 99.99% is the target) but it'll still be there if you try again later.
- idlewords 10y agoThe point is that at eleven nines, you're entering the realm of very rare/unlikely events that will also affect durability. In other words, there's a lack of humility about "unknown unknowns".
- notatoad 10y agobut amazon doesn't offer eleven 9s of availability. I don't think anybody serious does, so arguing how silly eleven 9s of availability is is kind of pointless. The SLA is only four 9s of availability.
- agrajag 10y agoNot even four 9's - they only trigger SLA credits when they dip below 3 9's.