The toughest Flash NAND memory chip is the SLC. Each memory cell can contain one one bit of data, so it explains why it can then support up to 100,000 writing cycles. Unfortunately, its manufacturing is rather expensive per GB and it is currently used in Pro-dedicated SSDs that are vey expensive. For the "customer" market, SSD are built from MLC that can store 2 bits per cell> production cost are lower, however lifetime of a cell is around 5,000 cycles for memory engraved at 25 nm.
Recently, MLC X3 and even X4 cells have been developed named after their ability to store respectively 3 or 4 bits per cell, making the production cost even cheaper per GB. So if price goes down, reliability too, and this is why there was no SSD using such cells up to now on the market.
Indeed, Kingston just announced its HyperX X3 SSD series. Based on a SandForce controller, they offer similar performance levels than SSD based on X2 cells, but with lower lifetime. Kingston tries to communicate on this aspect with the following information:
- 90 GB: 57.6 TB, so in average 52 GB per day for 3 years,
- 120 GB: 76.8 TB, so in average 70 GB per day for 3 years,
- 240 GB: 153.6 TB, so in average 140 GB per day for 3 years,
- 480 GB: 307.2, TB, so in average 280 GB per day for 3 years.
On paper, such volume of written data per day is more than enough for 95% of users, but it remains to be seen if such SSD will find their way on the market and seduce users. Their prices will most likely be one of the driving forces for their future success. If they are significantly cheaper, then they might become the new entry-level models while bringing more people to SSD.