Thursday 19 June 2008 — This is more than 16 years old. Be careful.
The next time someone inquires about how reliable your system is, say this:
We’re almost at five 9’s: we’re at five 8’s!
If you don’t know what I’m talking about, the Wikipedia article on uptime explains it pretty well: “Five nines” refers to a system being available 99.999% of the time, and is considered really good. “Five eights” would be 88.888% of the time, which would be horrible, and is in no way considered “almost” five nines.
Comments
This is proportionally harder to achieve when you have a system with multiple dependencies. E.g. If you need to validate users against an authentication system (OpenId), fetch data from an external service (POP mail servers), and save data to a persistent data store (Amazon S3), you would need each of those systems to sustain closer to six nines for the system to boast 5-nines reliability.
Any thoughts on whether or not 5-nines is harder or easier to achieve in the era of the Web 2.0? The technology we rely on has matured certainly, but web services are definitely becoming more intertwined.
I think these are much easier concepts for people to deal with. Moreover, as you can see by my last question, you quickly find yourself asking important questions that aren't necessarily directly impacted by downtime.
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