Joe Celko's Thinking in Sets: Auxiliary, Temporal, and Virtual Tables in SQL

2.2. Cheap Main Storage

Traditionally, main storage (older programmers called this “core memory” or “primary storage” and called tapes and disk “secondary storage,” while younger programmers call it “memory” and “storage,” respectively) was fast, but small and expensive in a computer. This is no longer true, since it is made from the same materials as the processors. The real problem today is managing the address space once you have reached a physical limit in the software and/or hardware. Here we have random access that does not require moving a physical read/write head to locate data.

There is still an open question as to when (or if) the cost of solid-state storage will become lower than magnetic media. To quote from Jim Gray’s interview: ...