3D stacked memory enters the mainstream.
Here we go. The very first mainstream drive with 3D NAND memory. So is it a revolution in solid-state storage or the same old 6Gbps SATA stagnation with a fancy name? The 850 EVO is the latest in Samsung’s affordable line of performance SSDs and shows its desire to push the solid-state game along, even at the lower end of the price/performance stack. Samsung has certainly nailed its colours to the mast when it comes to solid-state drives – it’s going to be first to market with new technologies, it’s going to aggressively drive prices down and it’s going to do it all alone.
To that end, the 850 Pro was the first consumer SSD to arrive on the scene with 3D stacked memory making up its various capacities. The EVO follows this trend, using another spin of the V-NAND technology for its more price-conscious range of SSDs. And, as is its wont, Samsung is keeping it all in-house and purely using its own technology – both its own memory and controllers – for these drives.
The new 3D V-NAND (Samsung is calling it vertical NAND) is designed to offer a path up to higher capacity SSDs in the coming years. The literal idea of stacked memory is to pile NAND chips on top of each other, with through-silicon vias (TSV) providing connections down directly through the stack. This helps boost the bandwidth, as the connections are physically closer, but also means higher capacity drives can be made without relying on the ever-shrinking of NAND modules which make up our SSDs.
Thanks for The memory
Samsung’s second-gen 3D V-NAND is made up of a full 32 layers stacked atop each other in each module. Those modules have a total density of 128Gb. Now, that’s not the highest density NAND you’ll find in today’s drives – both Crucial and Intel are throwing out drives with 128Gb density NAND in them and have partnered up to create their own 256Gb 3D NAND for 2015 – but the difference is Samsung is only using 40nm 3-bit MLC silicon to get there.
Because of the celebrated shrinking of production processes in all spheres of computing – from processors to memory to graphics chips – it might at first seem like this is a backwards step. We have, after all, become used to using 19nm NAND in our SSDs, so using a production process that’s twice as large would surely undo all the performance and efficiency boosts we picked up along the way down.
But because of 3D V-NAND’s ability to hit these high densities with such chunky lithographies, combined with the bandwidth boosts of the TSVs inside the stacked modules, the larger dies don’t impact relative performance. The efficiency gains from previous production shrinks are also largely offset by the power reductions in the switch from 2D to 3D NAND.
Samsung estimates a 30 per cent reduction in operational power with the Samsung 850 EVO compared with the older Samsung 840 EVO. The 40nm process comes into its own though when we start talking about endurance. The biggest benefit is the fact the larger production processes are more reliable and longerlived than their smaller descendents. When you’re making the switch, as Samsung is, from the 2-bit multi-layer cell (MLC) design of its higher-end 850 Pro to the less-robust 3-bit MLC, any endurance boost is welcome.
Close, but no Cigar
But what of performance? Sadly this is where we’re in a bit of a holding pattern with solid-state drives at the moment.
Because of the performance limitations of the SATA 6Gbps interface there’s a hard 600MB/s speed limit in place on connected drives. The Samsung 850 EVO is definitely quicker than the older Samsung 840 EVO, but not by the sort of performance metrics that are going to have you rushing out to upgrade if you’re rocking the last-gen drive.
The biggest change has been in the write performance of the new Samsung 850 EVO.
In sequential terms you’re looking at some 20 per cent quicker than the Samsung 840 EVO and a full 30 per cent quicker for the 4K random writes. Those are decent improvements and mean that in the realworld we saw our 30GB Steam folder transfer test resolve 22 seconds quicker than the Samsung 840 EVO.
Those are the results for the 500GB version of the Samsung 850 EVO, but the introduction of a new Samsung controller – the MGX – for the capacities of 500GB and below has been primarily tuned to provide consistent performance across the range. That means the performance of the cheaper 250GB version is almost identical.
When we’re talking about the generational update of an SSD range it’s natural to compare it to its predecessor, but arguably the more pertinent comparison is with the competition. The biggest competitor to the Samsung 850 EVO is Crucial’s MX100.
Crucial, along with its parent company Micron, is another big name in SSDs at the moment and its MX100 range is the price/ performance hero right now – especially in the 512GB capacity. It’s a tough battle with the 500GB Samsung 850 EVO, as both post similar synthetic numbers. This new Samsung drive is quicker in terms of sequential writes and 4K reads, but the difference is practically invisible in real terms. The Crucial drive doesn’t use any special caching shenanigans to hit its speeds, which explains why its real-world tests are quicker.
If you’re looking lower down the capacity stack it quickly becomes a no-brainer – the Samsung 850 EVO is clearly the go-to affordable SSD. It’s the quickest 250GB drive around and comes with a confidenceboosting five-year guarantee thrown in.
Overall, 850 EVO is the fastest mainstream, consumer-class SSD around. It’s just not quick enough to make it a killer upgrade over the previous generation EVO. Which is a shame.
|Samsung 850 EVO 500GB||Samsung 860 EVO 500GB||Crucial MX100 512GB||SanOisk Extreme Pro 680GB|
|Atto Peak Rd/Write (HB/s)||553/533||549/661||553/506||556/520|
|AS SSD Random Rd/Write (MB/s)||36/108||26/82||26/106||30/103|
|PCMark Expanded Storage Consistency (Index score)||6.676||6,317||6,291||4,929|
|Steam Folder Transfer (seconds)||208||230||191||191|
Best scores are bolded.
|Hamory controller||Samsung MGX|
|Memory||128Gb Samsung 40nm MLC|