With NVMe there is finally a successor to AHCI, which has been optimized for SSDs from ground up. Meanwhile there are affordable drive in the enthusiast segment available which benefit from this new standard. Therefore it’s interesting to have a look at RAID0 performance of two very fast NVMe drives. And this is exactly what we’re going to do on the following pages.
| Model | Samsung 950 Pro M.2 256 GB | Samsung 950 Pro M.2 512 GB | Samsung 950 Pro M.2 1 TB |
| Capacity | 256 GB | 512 GB | 1 TB |
| Form Factor | M.2 (2280) | M.2 (2280) | M.2 (2280) |
| Interface | PCIe 3.0 x4 | PCIe 3.0 x4 | PCIe 3.0 x4 |
| Protocol | NVMe | NVMe | NVMe |
| Controller |
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| Memory |
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| DRAM | 512 MB | 512 MB | n/a |
| Throughput |
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| Endurance | 200 TBW | 400 TBW | 800 TBW |
| Power Consumption |
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| Warranty | 5 Years | 5 Years | 5 Years |
Samsung is amongst the first companies which launched an NVMe SSD for end users. NVMe or NVM Express stands for Non-Volatile Memory Host Controller Interface Specification (NVMHCI). These specs define how solid state drives are being accessed through the PCI Express bus and therefore directly communicate with the CPU. NVMe replaces AHCI in the case of SSDs and it brings quite a few advantages to the table. AHCI, or Advanced Host Controller Interface, was optimized for drives with low throughput and high latencies. Apart from that it could not deal with high parallelism, being limited to a queue depth of 32. NVMe on the other hand has been designed to leverage the benefits of SSD from ground up, which means it can deal perfectly with low latency and high throughput drives. Apart from that it supports another magnitude of parallelism, whereas the queue depth can reach up to 65536. Since SSDs are based on controllers, which usually feature between eight and ten channels, parallelism is a key factor in gaining more performance.
Having a closer look at the specs we see that Samsung claims the 256GB 950 Pro M.2 can reach up to 2200/900MB/s sequential read/write speeds, which is simply a new level when it comes to the desktop market. Apparently this kind of performance in combination with a high-capacity drive doesnโt result in a bargain, which is why for instance the 512GB drive will set you back 319 Euro. Nevertheless, for this kind of money you really do get a drive, which outperforms almost anything available on the market to date and also offers a good amount of capacity.
A closer look at this M.2 expansion card shows, Samsung is using their 3 core ARM controller in the UBX version as well as second generation V-NAND memory. Therefore 32 layers of NAND flash memory are being stacked, which allows for 128Gbit of density. Per memory chip this translates into 128GB of capacity. At the moment Samsung is building 256GB as well as 512GB models. At a later stage, when the vendor switches to 48 layer V-NAND a 1 Terabyte drive is going to be available as well.