PCI EXPRESS & SSDs

Hard drives have seen their performance improve more than any other component over the last half-decade, all thanks to the popularization of solid state tech. Now, there’s a big leap forward that looks like it’s ready to become more widespread for consumers; SSDs that connect via PCI Express. Already used in some high-end systems, like the Mac Pro and a handful of Ultrabooks, these super-quick drives could soon be super-obtainable.

 

What is PCIe?

PCI Express (PCIe) stands for Peripheral Component Interconnect Express, a standard that was defined in 2004 by a collaboration which included Intel, IBM, HP and others. The connection, which is long and skinny (like a RAM slot), was developed to handle every type of internal card imaginable, from sound cards to video cards, and beyond. That meant the standard’s bandwidth had to be extremely high, and it also meant that each of the standard’s data channels had to handle data flowing in two directions at once.

A single PCIe 3.0 lane can handle almost a gigabyte of data per second, which means that a 4x slot can transfer about four gigabytes per second. PCI Express can handle up to sixteen lanes in a single slot, which equals nearly sixteen gigabytes of bandwidth. As if that wasn’t enough, the next version of the standard plans to double the per-lane bandwidth, raising the ceiling to 31.5 gigabytes per second across a 16-lane slot.

 

SATA6, by comparison, can only handle up to six gigabytes per second, which puts it at a huge disadvantage. Even Thunderbolt, which combines PCIe with DisplayPort into a single standard, can only manage about 1.25 gigabytes per second, per channel (the standard has two channels).

 

Why now?

All this talk of gigabytes and bandwidth makes PCI Express seem like a natural fit for hard drives. So natural, in fact, that you may be wondering why it was never used before.

 

This is partially due to the sudden rise in hard drive speeds. Prior to 2008, the year Intel released its first consumer SSD and kicked off the competition in that market, hard drives simply couldn’t saturate a single SATA connection. Even early solid state drives couldn’t thoroughly use a single SATA3 port.

 

The internal layout of desktops and laptops was different in 2004, as well. Expansion cards were far more common. Many systems had a sound card, a video card and a networking card, all of which took up space, and left little for other components. Today, however, these features are already integrated into the motherboard, or even (in some cases) the processor.

 

Finally, there’s an inertia to every standard that can be difficult to overcome. SATA and PCIe drives require different drivers to optimize their efficiency, and while hard drive companies know a lot about developing for SATA, they don’t have much experience developing for PCIe. Drive makers saw no need to spend money researching and developing new drivers for PCIe when SATA got the job done.

 

Now there is a need, however, because there’s no other obvious path forward. SATA can’t keep up with the advances of solid state performance, and is restricting the potential that drive makers can extract from their hardware. An alternative is needed, and choosing PCIe makes more sense than developing a brand new standard from scratch.

 

A PCI Express drive may not be in your immediate future, but the technology will be hard to avoid within a few years, taking hard drives to an entirely new level of performance.

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