I've always associated the term "primary storage" with main memory, so memory which can be accessed directly by the CPU and its of the volatile type. The past few days I've been reading some technical articles/publications where the term "primary storage" seems like it's used as synonym for secondary storage and in the Wikipedia page for Computer data storage it says:
Recently, primary storage and secondary storage in some uses refer to what was historically called, respectively, secondary storage and tertiary storage
So, I'm guessing that primary storage ≠ main memory and nowadays it's synonym with secondary storage which persist once the system is shut down. Is that correct ?
Also, one of the articles I was reading was: Deduplication for primary block storage