- 16 Jun, 2016
- Phil Hong
- 0 Comments
- hard drive, mobile, nvme, ssd,
SSDs have become standard fare in high performance computers. Aside from your internet connection the slowest part of a computer is the mechanical hard drive. Upgrading to a SSD is the best bang for your buck these days.
Recently I discovered NVMe SSDs which are basically super fast SSDs that have migrated away from the SATA port. Before getting into why SATA has become the bottleneck it’s important to understand the basic of an SSD. Historically hard drives were slow mechanical things that could only stream data a few bytes at a time. This is because mechanical hard drives store data on physical metal platters spinning at thousands of Revolutions Per Minute (RPM). To read and write this data they have to move mechanical heads to the right place on the platter before any data could start streaming. This process takes milliseconds but when you multiply that over the gigabytes and terabytes we are now storing, the mechanical hard drive becomes the main bottleneck in most computers.
Enter the SSD. The SSD is less like a hard drive and more like RAM, except once power is removed from a SSD the data remains intact. This gives you the best of both worlds: non-volatile memory and instant random access.
Now that SSDs have had years to improve they have quickly outgrown the infrastructure designed for mechanical hard drives, namely the SATA bus and the ACHI command protocol. The current SATA bus tops out at 6.0 Gb/s. Most modern SSDs can easily saturate the SATA bus.
Next-gen SSDs – NVMe SSD
Enter the new generation of SSDs called NVMe over PCIe. The new architecture utilizes the PCIe bus; the same bus utilized by high performance graphics cards.
The other bottleneck that needed to be alleviated was the data access protocol, ACHI. With a mechanical drive, disk I/O was limited to a single stream of data: whatever was being read by the disk head at that moment. This protocol was called AHCI. Flash memory does not use a moving head and can access any area of data instantly. The new protocol is called NVMHCI and can issue 65k simultaneous I/O requests, among other improvements.
The combination of these technologies allows computers to stream information from SSDs at a much faster rate. Current NVMe SSD drives can support 2500/1500 MB/s read/write speeds. That compares to regular SSDs coming in around 500/400 MB/s read/write speeds.
The downside to this new tech is that most motherboards don’t support it yet. I know all of my current computers don’t have the right hardware. When it comes time to buy a new computer you can be sure I’m looking for NVMe SSD support.
PC Gamer – http://www.pcgamer.com/best-nvme-ssds/
Wikipedia page – https://en.wikipedia.org/wiki/NVM_Express