Testing SATA Express And Why We Need Faster SSDs
by Kristian Vättö on March 13, 2014 7:00 AM EST- Posted in
- Storage
- SSDs
- Asus
- SATA
- SATA Express
Why Do We Need Faster SSDs
The claim I've often seen around the Internet is that today's SSDs are already "fast enough" and that there is no point in faster SSDs unless you're an enthusiast or professional with a desire for maximum IO performance. There is some truth to that claim but the big picture is much broader than that.
It's true that going from a SATA SSD to a PCIe SSD likely won't bring you the same "wow" factor as going from a hard drive to an SSD did, and for an average user there may not be any noticeable difference at all. However, when you put it that way, does a faster CPU or GPU bring you any noticeable increase in performance unless you have a usage model that specifically benefits from them? No. But what happens if the faster component doesn't consume any more power than the slower one? You gain battery life!
If you go back in time and think of all the innovations and improvements we've seen over the years, there is one essential part that is conspicuously absent—the battery. Compared to other components there haven't been any major improvements to the battery technology and as a result companies have had to rely on improving other components to increase battery life. If you look at Intel's strategy for its CPUs in the past few years, you'll notice that mobile and power saving have been the center of attention. It's not the increase in battery capacity that has brought us things like 12-hour battery life in 13" MacBook Air but the more efficient chip architectures that can provide more performance while not consuming any more power. The term often used here is "race to idle" because ultimately a faster chip will complete a task faster and can hence spend more time idling, which reduces the overall power consumption.
SSDs are no exception to the rule here. A faster SSD will complete IO requests faster and will thus consume less power in total because it will be idling more (assuming similar power consumptions at idle and under load). If the interface is the bottleneck, there will be cases when the drive could complete tasks faster if the interface was up for that. This is where we need PCIe.
| Our Hypothetical Laptop | ||
| Power Consumption | Light Use | Heavy Use |
| Whole Laptop | 7W | 20W |
| SSD | 1W | 3W |
Our hypothetical laptop spends 80% of its time in light use and 20% of the time under heavier load. With such characteristics, the average power consumption comes in at 9.6W and with a 50Wh battery we should get a battery life of around 5.2 hours. The scenario here is something you could expect from an ultraportable like the 2013 13" MacBook Air because it has a 54Wh battery, consumes around 6-7W while idling and manages 5.5 hours in our Heavy Workload battery life test.
Now the SSD part. In our scenario above, the average power consumption of our SSD was 1.4W but in this case that was a SATA 6Gbps design. What if we took a PCIe SSD that was 20% faster in light use scenario and 40% in heavy use? Our SSD would spend the saved time idling (with minimal <0.05W power consumption) and the average power consumption of the SSD would drop to 1.1W. That's a 0.3W reduction in the average power consumption of the SSD as well as the system total. In our hypothetical scenario, that would bring a 10-minute increase in battery life.
Sure, ten minutes is just ten minutes but bear in mind that a single component can't do miracles to battery life. It's when all components become a little bit faster and more efficient that we get an extra hour or two of battery life. In a few years you would lose an hour of battery life if the development of one aspect suddenly stopped (i.e. if we got stuck to SATA 6Gbps for eternity), so it's crucial that all aspects are actively developed even though there may not be noticeable improvements immediately. Furthermore, the idea here is to demonstrate what faster SSDs provide in addition to increased performance—in the end the power savings depend on one's usage and in workloads that are more IO intensive the battery life gains can be much more significant than 10 minutes. Ultimately we'll also see even bigger gains once the industry moves from PCIe 2.0 to 3.0 with twice the bandwidth.
4K Video: A Beast That Craves Bandwidth
Above I tried to cover a usage scenario that applies to every mobile user regardless of their workload. However, in the prosumer and professional market segments the need for higher IO performance already exists thanks to 4K video. At 24 frames per second, uncompressed 4K video (3840x2160, 12-bit RGB color) requires about 900MB/s of bandwidth, which is way over the limits of SATA 6Gbps. While working with compressed formats is rather common in 4K due to the storage requirements (an hour of uncompressed 4K video would take 3.22TB), it's not uncommon for professionals to work with multiple video sources simultaneously, which even with compressing can certainly exceed the limits of SATA 6Gbps.
Yes, you could use RAID to at least partially overcome the SATA bottleneck but that add costs (a single PCIe controller is cheaper than two SATA controllers) and especially with RAID 0 the risk of array failure is higher (one disk fails and the whole array is busted). While 4K is not ready for the mainstream yet, it's important that the hardware base be made ready for when the mainstream adoption begins.
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willis936 - Friday, March 14, 2014 - link
A 4.5GHz 4770k doesn't render my video, crunch my matlab, and host my minecraft at arbitrarily amazingly fast speeds, but it's a big step up from a Q6600 :pMrBungle123 - Friday, March 14, 2014 - link
That cable looks horrible, I'd rather them just move SSD's to a card.TEAMSWITCHER - Friday, March 14, 2014 - link
Second That! Hardware makers need to abandon SATA Express and start working on new motherboard form factors that would allow for attaching the flash drives directly to the motherboard. SATA Express is another compromised design-by-committee. Just what the struggling PC industry needs right now! Jeepers!!!iwod - Friday, March 14, 2014 - link
The future is Mobile. Where Laptop already overtook Desktop in numbers. So why another chunky ugly old hack for SSD? Has Apple not taught them a lesson where Design matters?And the speed, It is just too slow. We should at least be at 16Gbps, and since any of these standard aren't even coming out fast enough i would have expected the interface to leap to 32Gbps. Plenty of headroom for SSD Controller to improve and work on. And Intel isn't even bundling enough PCIe Lanes direct from CPU.
Why cant we build something that is a little future proof?
willis936 - Friday, March 14, 2014 - link
Cost matters. The first thing they'll tell you in economics 101 is that we live in a world with finite resources and infinite wants. There's a reason we don't all have i7 processors, 4K displays, and 780 GPUs right now. Thunderbolt completely missed it's window for adoption because the cost vs. benefit wasn't there and OEMs didn't pick it up. The solutions will be made as the market wants it. The reason the connector is an ugly hack is so you can have the option for high bandwidth single drives or multiple slower drives. It's not pretty and I'd personally like to just see it as a phy/protocol stack that uses the PCIe connector with some aneg to figure out if it's a SATAe or PCIe device but that might cause problems if PCIe doesn't handle things like that already.Your mobile connector will come, or rather is already here.
dszc - Saturday, March 15, 2014 - link
Thanks Kristian. Great article.I vote for PCIe / NVMe / M.2. SATAe seems like a step in the wrong direction. Time to move on. SATA SSDs are great for backward compatibility to help a legacy system, but seem a horrible way to to design a new system. Too big. Too many cables. Too much junk. Too expensive. SATAe seems to be applying old thinking to new technology.
watersb - Sunday, March 16, 2014 - link
I don't get the negative reactions in many of the comments.Our scientific workloads are disk-IO bound, rather than CPU-bound. The storage stack is ripe for radical simplification. SATAe is a step in that direction.
rs2 - Sunday, March 16, 2014 - link
This will never fly. For one thing the connectors are too massive. Most high-end mainboards allow 6 to 8 SATA drives to be connected, and some enthusiasts use nearly that many. That will never be possible with the SATAe connector design; there's just not enough space on the board.And the consuming 2 PCI-E lanes per connector is the other limiting factor. It's a reasonable solution when you just need one or two ports. But in the 8-drive case you're talking about needing 16 extra lanes. Where are those meant to come from?
willis936 - Sunday, March 16, 2014 - link
How many ssds do you plan to use at once? I can't think of a single use case where more than one ssd is needed, or even wanted if bandwidth isn't an issue. One ssd and several hard drives is certainly plausible. So there are 6 instead of 8 usable ports for hard drives. How terrible.Shiitaki - Monday, March 17, 2014 - link
So exactly what problem is this fixing? The problem of money, this is a pathetically attempt at licensing fees. SSD manufacturers could simply change the software and have their drives appear to the operation system as a pci-e based sata controller with permanently attached drive TODAY. It would her genius to be able to plug a drive into a slot and be done with it. We don't need anything new. We already have m-pci-e. Moving to a m-pci-ex4 would have been a better idea. The you could construct backplances with the new m-pci-ex4 connectors that aggrate and connect to a motherboard using a lci-ex8/16 slot.This article covers the story of a organization fighting desperately to not disappear into the history books of the computer industry.