Hitachi Global Storage to Demo First 12Gb/s SAS SSD

Hitachi Global Storage Technology (HGST), which was recently acquired by Western Digital, claims to be first with a demonstration of the first 12Gb/s SAS SSD. The company will be unveiling the device at the SCSI Trade Association Technology Showcase, which take place in Santa Clara on May 9.
As the name indicates, the drive is theoretically capable of transferring data at 12 Gb/s - twice the rate of current 6 Gb/s drives - which translates to a total bandwidth of 4.8 GB/s.
“We have successfully achieved interoperability between our 12Gb/s SAS drive and 12Gb/s SAS HBAs and expanders from both LSI and PMC-Sierra,” said Brendan Collins, vice president of HGST product marketing, in a prepared statement. “Meeting these interoperability milestones is critical when preparing the industry for the adoption of a new interface standard."
HGST said that it expects market adoption of 12 Gb SAS drives in 2013.
Gb/s is not the same as GB/s
As is typically the case with news bits here, this is woefully short on details or expected further explanations.
Peak performance of 6Gb/s SAS is actually 24Gb/s using link aggragation which basically bundles 4 ports together. Like other current serial interfaces (SATA/USB), for every 10bit packet, 8bits are actually data. So out of the theoretical bus transfer limit of 3GB/s, 2.4GB/s would be the usable data transfer rate. Just double this to get the 4.8GB/s rate quoted in this article for the new 12Gb/s SAS standard.
SATA and SAS have the exact same bandwidths. So, if this is an SAS or a SATA 12Gb/s device, it means that at best, it can transfer at 1.2GB/s. In order for it to have 4.8GB/s, it would need at least four SATA/SAS 12Gb/s ports.
So yes blazorthon, you're right. Another example of an interface that uses 8/10 encoding is PCIe, that is up until the PCIe 3.0 specification which has a 128/130 bit encoding. IE, a PCIe 2.0 lane has a 5Gb/s connection between the two devices on either end, but only 4Gb/s is actually usable for transferring data between either side because the extra 1Gb/s is used for error correction in the data. PCIe has an 8Gb/s connection, but it's change to a 128/130 bit encoding allows it to have an almost double the bandwidth of PCIe 2.x.
Yet another common interface that uses 8/10 is USB.
Not everyone wants to spend a huge premium for a PCIe drive when it probably won't help most people (not even most consumer SSD users) much more than a SATA SSD does. The whole point of the SSDs is to be far better than a hard drive. Any improvements after that only help greatly for more specific tasks and are usually not justifiable purchases for most consumers.
everyone here seems to know that.
while not totally accurate this is correct. But i do believe sas uses multi channels so the artical could be correct.
SAS is not the old SCSI you're thinking of. It's uses the same connectors as SATA. It has tons more features. It recognizes SATA drives. It's full-duplex instead of half (SATA).
It's nothing to do with 1,000 vs. 1,024. It's that there are 10 bits per byte instead of 8.
Yeah i was wondering that too
But if the 12Gbps SAS drive is aimed at the consumer market i will be wondering where they are getting consumer boards have a SAS port to hook it up to and even if they do the SAS controller cards are still almost as much as buying another hard drive.
Very good step in hard drive transfer speed but timing is not that good in the development for it. Also how is it in RAID 3, 5, 6, 8 and 10?
Most servers have SAS connectivity, be it through the motherboard, or through a PCIe RAID card and it's fairly cheap to replace a RAID card if you sell the current one, or at least put it to use somewhere else. It's even better if you just use this drive in new systems instead of upgrading old systems. No SAS drive is aimed at the consumer market. You're not supposed to RAID most SSDs. This has nothing to do with hard drives and is not a hard drive.
Divide by ten, not eight. SATA, like many other serial interfaces, uses 8/10 bit encoding and thus each 8 bit byte of data transferred is transferred as a ten bit byte for improved error correction. So, it maxes out at 600MB/s. SAS does the same. That's why no SATA6Gb/s and SAS6Gb/s SSDs can ever breach 600MB/s. A single SAS 12Gb/s port can hit 1.2GB/s as a maximum theoretical transfer speed. Four SAS ports can hit 4.8GB/s in maximum theoretical aggregate throughput.
Not that I'm knocking the development of the new interface. You need both the interface and the storage for a system to work.