As storage systems grow larger and larger, protecting their data for long-term storage is becoming more and more challenging.

摘要

David S. H. Rosenthal, Stanford University These days, we are all data pack rats. Storage is cheap, so if there's a chance the data could possibly be useful, we keep it. We know that storage isn't completely reliable, so we keep backup copies as well. But the more data we keep, and the longer we keep it, the greater the chance that some of it will be unrecoverable when we need it. There is an obvious question we should be asking: how many copies in storage systems with what reliability do we need to get a given probability that the data will be recovered when we need it? This may be an obvious question to ask, but it is a surprisingly hard question to answer. Let's look at the reasons why.