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Amazon explains here: http://aws.typepad.com/aws/2010/05/new-amazon-s3-reduced-redundancy-storage-rrs.html http://aws.typepad.com/aws/2010/05/new-amazon-s3-redu

by jzwinck 12y ago

Amazon explains here: http://aws.typepad.com/aws/2010/05/new-amazon-s3-reduced-redundancy-storage-rrs.html http://aws.typepad.com/aws/2010/05/new-amazon-s3-reduced-red... "If you store 10,000 objects with us, on average we may lose one of them every 10 million years or so."

gjm11 12y ago
Which is of course rubbish; events like the sudden fall of civilization, large-scale nuclear war, all governments on earth suddenly declaring very large computing or storage facilities illegal out of paranoia about runaway AI, etc., are surely much more probable than 10^-11 per year and have the potential to wipe out S3 entirely. It's arguable that all of these are sufficiently major events that if any of them happens you won't care that you just lost all your data stored in S3 because you'll be too busy fighting off wolves, dying of radiation sickness, or whatever. More to the point, though, I take it the real point of these many-9s guarantees is that if you store a very very large number of things on S3 the danger of losing one of them is still very small. So, for instance, if you store 10^8 objects in S3 then the probability of losing any of them in a given year is allegedly about 0.1%, which is actually fairly credible. (But when that happens, a substantial fraction of the time it's because of a really major disaster and you probably lose a lot more than one object.) We could do with more precise ways of describing availability guarantees, to distinguish between a small probability of losing lots of data and a large probability of losing a tiny amount of data.
- ceejayoz 12y ago
  That argument applies to any uptime guarantee from any vendor. When Rackspace says "99.9% uptime!" no one complains that they should have to say "unless nuclear war happens".
  - gjm11 12y ago
    If the figure is 99.9% then I don't think it needs any such disclaimer; large-scale nuclear war is pretty improbable these days. It's only once you start getting to large numbers of 9s that these spectacular low-probability events begin to matter.
    - dmd 12y ago
      > pretty improbable these days http://upload.wikimedia.org/wikipedia/commons/4/4b/Doomsday_Clock_graph.svg http://upload.wikimedia.org/wikipedia/commons/4/4b/Doomsday_...
  - Spooky23 12y ago
    There's a difference between setting a 99.9% uptime on a monthly basis vs. implying that my data will be safe for a period of time exceeding the existence of humans as a species.

by jzwinck 12y ago

gjm11 12y ago

Which is of course rubbish; events like the sudden fall of civilization, large-scale nuclear war, all governments on earth suddenly declaring very large computing or storage facilities illegal out of paranoia about runaway AI, etc., are surely much more probable than 10^-11 per year and have the potential to wipe out S3 entirely. It's arguable that all of these are sufficiently major events that if any of them happens you won't care that you just lost all your data stored in S3 because you'll be too busy fighting off wolves, dying of radiation sickness, or whatever. More to the point, though, I take it the real point of these many-9s guarantees is that if you store a very very large number of things on S3 the danger of losing one of them is still very small. So, for instance, if you store 10^8 objects in S3 then the probability of losing any of them in a given year is allegedly about 0.1%, which is actually fairly credible. (But when that happens, a substantial fraction of the time it's because of a really major disaster and you probably lose a lot more than one object.) We could do with more precise ways of describing availability guarantees, to distinguish between a small probability of losing lots of data and a large probability of losing a tiny amount of data.

ceejayoz 12y ago
That argument applies to any uptime guarantee from any vendor. When Rackspace says "99.9% uptime!" no one complains that they should have to say "unless nuclear war happens".
- gjm11 12y ago
  If the figure is 99.9% then I don't think it needs any such disclaimer; large-scale nuclear war is pretty improbable these days. It's only once you start getting to large numbers of 9s that these spectacular low-probability events begin to matter.
  - dmd 12y ago
    > pretty improbable these days http://upload.wikimedia.org/wikipedia/commons/4/4b/Doomsday_Clock_graph.svg http://upload.wikimedia.org/wikipedia/commons/4/4b/Doomsday_...
- Spooky23 12y ago
  There's a difference between setting a 99.9% uptime on a monthly basis vs. implying that my data will be safe for a period of time exceeding the existence of humans as a species.