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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.

  • blazorthon
    Isn't SATA 6Gb/s 600MB/s maximum and SAS 6Gb/s equal to SATA 6Gb/s in bandwidth? So shouldn't SAS and SATA 12Gb/s be 1.2GB/s per port? It should take four such ports to hit 4.8GB/s as a theoretical maximum.
  • drwho1
    are we talking sata 4?
  • TidalWaveOne
    Since when does 12 Gb/s equal a total bandwidth of 4.8 GB/s? My math must be off (or someone who wrote this piece).
  • tului
    This is SAS 12Gbps, but I would imagine SATA 12Gbps won't be far behind. Given that the current Sandforce SSDs can saturate 6Gbps SATA now it is needed.
  • prononbiasedgamerenthusiast
    Sandforce controllers rely on better flash
  • cbrunnem
    TidalWaveOneSince when does 12 Gb/s equal a total bandwidth of 4.8 GB/s? My math must be off (or someone who wrote this piece).
    Gb/s is not the same as GB/s
  • this probably refer to sas wide port which consists of 4 ports to achieve 4.8GB/s. For this SSD, i don't think they use wide port, so the theoretically, it can goes as high as 1.2GB/s.
  • kinggremlin
    TidalWaveOneSince when does 12 Gb/s equal a total bandwidth of 4.8 GB/s? My math must be off (or someone who wrote this piece).
    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.
  • alphaalphaalpha
    For everyone who's wondering, SATA has an 8/10 bit encoding (in order to transfer eight bits of data aka one byte, it encodes that eight bits into a ten bit word for improved error correction), so 6Gb/s in SATA means 600MB/s for real data transfer (MB meaning 1000^2 instead of 1024^2), so 6Gb/s means 600MB/s in maximum theoretical transfer bandwidth. SATA also happens to be full duplex, so it's 600MB/s in both ways (to and from the hard drive).

    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.
  • kronos_cornelius
    Thanks for the discussion on what the speed means commenters. It remains a better choice to just pick a high transfer PCIe SSD since those speeds are well above 600MB/s.