Upcoming Computing Technology: SATA Express
In part three of our Upcoming Computing Technology series, courtesy of our server supplier Supermicro NZ, this week we are looking at the next generation of PC-grade drive connections. I say PC-grade, because in a server you’ll often find SAS in use instead of SATA, purely due to the greater capabilities of SAS drives.
This is what Supermicro had to say about the second of these developments, SATA Express (SATAe):
“SATA Express 16Gb/s is an interesting development that will eventually succeed SATA3 6Gb/s. Instead of doubling the speed of SATA3 it will use PCI-Express connectivity to reach speeds of 1969MB/s for SATA Express storage devices (i.e. SSDs) while keeping compatibility with older SATA3 6Gb/s SSDs and HDDs. This is equivalent to 3.2x faster than SATA3 at 600MB/s and is made possible by using two PCI-Express 3.0 x2 lanes.“
As I mentioned last week, SATA is one particular drive connection type. Though SATA drives are much cheaper than their SAS counterparts – also offering higher storage capacities – their performance isn’t quite as flash as the SAS alternative. This makes them much better suited to being used in regular PCs, such as office workstations.
In addition to this, there are two types of drives: Hard Disk Drives (HDDs) and Solid State Drives (SSDs). SATA was originally designed for HDDs, which although much cheaper than their SSD equivalents, contain mechanical components that give them vastly slower performance than SSDs. As SSD drives continue to improve in performance, the SATA connection speed will quickly become a bottleneck that hinders the SSDs from reaching their full performance potential. Now it isn’t always a bottleneck quite yet, because the drive circuitry itself is often not fast enough to saturate the link; however there are some drives which do saturate the link and would benefit from SATAe.
To understand the benefit of SATAe, think of a super-powered worker (the SSD) throwing boxes (data) onto a conveyor belt (SATA). The worker wants to put a number of boxes on the conveyor belt at once, but the conveyor belt is too slow and confined to take as many boxes as desired. Improving the performance of SATA (speeding up the conveyor belt) would take drive manufacturers a long time, so what the designers have done is make use of another interface (PCI-Express) to create SATAe and allow for a much greater transfer of data at one time (equivalent to installing multiple conveyor belts). This way the requirements of both SSDs and HDDs can be served without hindering one or the other.
That’s it for SATA. Next week I’ll touch on the fourth and final development, NVM Express (NVMe)