Storage Class Memory

Storage Class Memory

Storage Class Memory is an emerging non-volatile memory segment positioned between the most successful system memory (DRAM) and the most successful silicon storage (NAND Flash).

Ideally, Storage Class Memory has DRAM (speed & endurance) and NAND Flash (cost & retention) characteristics. However, this utopia may never see the light of day.

There are many opportunities for new memories in the vast space between DRAM and NAND Flash, each with different speed, endurance and retention metrics. The 2 most extreme opportunities are “The space close to NAND Flash” and “The space close to DRAM”, each with different priorities for systems with respect to speed, endurance, and retention:

Retention is everything in the space close to NAND Flash, while reaching a higher speed than NAND Flash is the opportunity for which system companies may be willing to pay a higher price per gigabyte. Whatever endurance this results in may be acceptable.

Speed is everything in the space close to DRAM, while reaching an endurance as close as possible to DRAM is the opportunity, especially if this reduces the need for more expensive DRAM in systems. Whatever retention this results in may be acceptable.

The main reason that retention is far less critical than speed and endurance is the space close to DRAM is that DRAM is essentially a volatile memory. Its contents need to be read and written back (refreshed) every 60 milliseconds and any retention better than DRAM saves power. The reality is that a Storage Class Memory with a retention of just one day is an astonishing 1.5 million times (or 6 orders of magnitude) better than DRAM retention. A Storage Class Memory with a retention of 1 week, 1 month, or 1 year further boosts this to 10 million, 44 million, and half a billion respectively.

The biggest opportunities are always where the pain is the highest and that is in the space closest to DRAM. The ultimate market demand is therefore for Storage Class Memory with DRAM speed, the highest endurance achievable with this speed, a cost per gigabyte closer to NAND Flash, and a pragmatic retention far superior to DRAM retention.

Storage Class Memory Requirements

To achieve revenue similar to DRAM and NAND Flash, Storage Class Memory must have the following characteristics: