Two New SATA Specs: SATA Express & µSSDby Anand Lal Shimpi on August 11, 2011 12:22 AM EST
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- SATA Express
The SATA IO working group announced one new spec and that it has begun work on another: µSSD and SATA Express, respectively. These two specs span the gamut from ultra mobile devices all the way to high end PCs and servers. Let's tackle the smaller one first.
Tablets and smartphones are quickly becoming very powerful. We'll see another 20 - 50% gain in CPU performance in the next 12 months, and chances are we'll see a repeat performance another 12 - 18 months after that. As we've learned from the PC industry, increases in processor performance must be met with faster memory and IO. We're already running into IO bottlenecks on tablets. Copying large videos and audio to the current generation of tablets is a pain, with write speeds averaging less than 20MB/s. Faster storage is necessary.
The µSSD spec simply introduces a standard electrical interface for SATA on BGA devices. Currently if you want to connect a SATA controller to a SATA device you use a physical connector, whether standard SATA, micro or mini SATA. Either way it's a big physical connector. With µSSD the SATA interface is in the ball-out of a BGA chip on a motherboard, there's no physical external connector - just route the traces from your SSD to your SATA controller.
What we'll see going forward is integrated SATA controllers in SoCs, which will now have the option of interfacing with either a standard SATA SSD or a µSSD soldered onto the motherboard. The latter is more desirable for ultra small form factors. SanDisk has already been shipping a µSSD compliant device: its iSSD. Expect others to follow.
The next interface is SATA Express. This one is designed to keep SATA relevant while allowing for the growth of high performance SSDs. It took SandForce all of one year to release a controller that could saturate a 6Gbps SATA interface. Many companies have turned to PCI Express as a solution to offer more bandwidth than a single SAS/SATA port can deliver. SATA Express is designed to fix this issue.
The spec won't be complete until the end of the year, but it will allow for two new SATA speeds: 8Gbps and 16Gbps as well as backwards compatibility with existing SATA devices. SATA Express will leverage PCIe 3.0 for higher operating speeds, perhaps indicating that it'll layer on top of PCIe rather than remain as an independent interface. If the spec is completed at the end of this year, don't expect to see controller support until mid to late next year at the earliest. It'll take a while for SSDs to natively support the standard as well.
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MikhailT - Thursday, August 11, 2011 - linkI’m slightly confused here but I don’t think we’ll get an answer until the final spec is released at the end of the year. It sounds like SATA-E will compliment the current SATA-III ports, it isn’t designed to replace it. So, we might get desktops with 2xSATA-E and 8xSATA-iII ports instead of 8xSATA-E.
I doubt we’d see any widespread support until 2015. Laptops are being sold more than desktops and they traditionally lag behind new interface support.
I think Apple is likely to support the uSATA standard for MBA/iPad first on the market. It’d be interesting to see how it all work out in the end.
icrf - Thursday, August 11, 2011 - linkI could see Apple putting it in the MBA, but just as much because it means they can solder in the SSD and kill the after market.
DanNeely - Thursday, August 11, 2011 - linkCome on now. We all know the real reason is that it will let them either reduce the laptops volume by at least 10-20mm^3 or alternately increase the battery volume by the same amount.
name99 - Thursday, August 11, 2011 - linkRight, the LUCRATIVE MBA SSD market. Plenty of companies are getting rich off that right now. You do understand how MBA SSDs work?
Perhaps you'd like to tell us next about all those people getting rich selling SSDs to put into iPads.
Anand Lal Shimpi - Thursday, August 11, 2011 - linkCorrect, I think you'll only get full bandwidth to one or two ports at most on a desktop board. The spec will likely be backwards compatible though, so you'll be able to use a 6Gbps SATA drive on all ports.
Jambe - Thursday, August 11, 2011 - linkIs the actual silicon involved in a native PCIe controller more expensive than sata controllers, or is it just the R&D costs involved atp?
I would love to have a PCIe SSD in conjunction with bulk disk storage on SATA.
iwod - Thursday, August 11, 2011 - linkI have been calling for this for a long time.
8 / 16Gbps is basically PCI-E 3.0 1x and 2x.
PCI-E is actually Full Duplex, unlike the Half Duplex SATA Connection, which would become a problem in high speed data transmission.
PCI-E is a powered connection. No more additional power plug for SSD devices.
I believe they should have used PCI-E 4x as well, giving 4GB/s connection. Although they could just let PCI-E 4.0 2x in the future to handle it.
But Given we are finally moving to PCI-Express. And SATA protocol has no relevance with the inner of SSD working. Why are we still sticking with SATA then? Apart from Software compatibility reason.
I am also not aware of any Power Management features in PCI-E that go down to the level of SSD which are mW. Or has PCI-E 3.0 changed that?
Now i just hope they could fast track the release. So Ivy Bridge MB maker will be well prepared.
FaaR - Thursday, August 11, 2011 - linkSATA is, and always has been full duplex. It has separate send and receive wires in the cable.
zorxd - Thursday, August 11, 2011 - linkAnyway the drive itself is half duplex. You can't write to a location while you are reading an other one.
Metaluna - Thursday, August 11, 2011 - linkFull duplex would still be useful when you're using port multipliers or SATA/SAS expanders, where you are communicating with more than one independent drive over a single cable, and some might be reading or writing at the same time. I don't know enough about port multipliers to say if they exploit the capability though.
Also with full duplex you can in theory issue new commands to the drive while a read is underway. Again, don't know enough about the SATA protocol to say if this is done.