http://yumianfeilong.com/html/2012/03/13/552.html
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Last year, Nat and I went to the Royal Geographical Society’s Explore conference. One of the sessions was about surviving in the desert with camels, and the point was made that you should always take three camels in to the desert with you. That way, if one of them breaks its leg and another one runs off you can still make it out safely.
When the Guardian hosted UK ScaleCamp a few months later, the same principle came up again - this time referring to data. If your data is on one machine (or in just one data centre), you have a high risk of losing it no matter how well specced that individual machine is. If it’s being served from two machines you’re still at risk - if one of them dies, the other one is dramatically more likely to die shortly afterwards since it now has to handle twice the load.[/php] |
