Samsung adds 3D NAND to its most affordable SSD
The new 850 EVO SSD is a follow-on to the 840 EVO released last year. The predecessor used 2D planar NAND, but the new 850 version uses NAND stacked 32 layers high in a 7mm height form factor drive.
VNAND technology is expected to reach 100 levels of stacked NAND cells by 2017. That will offer a 1Tbit per chip density, compared to today's 2D planar density of 250Gbits per chip.
The drive still stores three bits of data per transistor, as did its predecessor.
"We initially were targeting the drive at the consumer desktop or as a notebook upgrade drive, but now with the performance and reliability, we're also able to target the gamer and heavier write user," said Richard Narz, a Samsung senior marketing manager.
Samsung has also incorporated its "TurboWrite technology" in the 850 EVO, which it said boosts performance random writes over its predecessor by 1.9 times.
The 850 EVO can reach random read speeds of more than 98,000 I/Os per second and 90,000 random write IOPS, Samsung stated on a spec sheet. The SSD's top sequential read speed is 540 MBps and its top write speed is 520 MBps on all capacities of the drive.
Because the NAND is stacked vertically, the transistors or NAND cells (where bits are stored) are less closely packed together, an architecture that increases drive reliability.
Narz said endurance in the 850 EVO is twice that of the previous 840 drive. The new SSD also cuts energy consumption by 30%. During an average data read, the drive uses a maximum of 3.7 watts and 4.4 watts during writes. While idle, the SSD uses 2 milliwatts of power.
Because of the greater endurance, the warranty on the 850 EVO is five years, compared with Samsung's former three-year guarantee. The 850 EVO comes in 120GB, 250GB, 500GB and 1TB models. The 250GB model can sustain 40GB worth of writes per day and up to 75TB over a five-year lifetime, Narz said. The 1TB model can sustain 80GB of writes per day and up to 150TB of writes over its lifetime, he said.
The predecessor to the new 850 EVO SSD - the 840 EVO - experienced performance problems soon after its release last year. Samsung issued a firmware fix for the drive.
The 840 EVO hit the market with a sub-$1 per gigabyte price tag. For example, a 1TB version retailed for $599. The new 850 EVO takes that price down by $100.
The 120GB retails for $99.99, the 250GB for $149.99, the 500GB for $269.99, and the 1TB model for $499.99.