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Supermicro New Zealand
USB 3.0, SATA 6Gb/s & Lightpeak
31 May 2010
This newsletter provides an overview on the latest connectivity interfaces that are becoming more widely available in motherboards, add-on cards and peripherals. It is important to note however that some of the currently available implementations do not handle the technologies in a native fashion and therefore do not offer the theoretical maximum speeds discussed below.
- SATA revision 3.0: The main improvement is the increased raw transfer rate of 6 gigabits per second which equates to around 600MB/s after we take into account the encoding overhead. SATA 3.0 is also known as SATA 600 or SATA 6Gb/s. While this does not improve upon the performance of the current mechanical hard disk drives, the increasingly popular SSD drives are already getting very close to the SATA 300 limit of 300MB/s. For example, the Intel X25-E SSD provides a sustained sequential read of up to 250 MB/s. In short, performance benefits are still very limited as of today, but the new specification is backwards compatible.
- USB 3.0: Also known as SuperSpeed USB as opposed to High-Speed for USB 2.0, the new specification offers 10x the performance over the older specification by supporting a transfer speed of up to 480MB/s. The performance of hard disks have been limited by USB 2.0 for a while now as a typical hard drive can have an upper performance range of around 120MB/s while USB 2.0 only supports up to 60MB/s*2. USB 3.0 will be an important feature for most people who are looking to upgrade their workstations / laptops in the near future. It is important to note that USB 3.0 connectors are generally backwards compatible, but include new wiring and full duplex operation. It is backwards compatible with existing peripherals and cabling but such setups will be restricted at the old speed.
- Lightpeak: Intel's code-name for a new high-speed optical cable technology that promises to provide 10Gb/s speeds with the potential to scale to 100Gb/s. Intel is promoting it as the next-generation replacement for SCSI, SATA, USB, FireWire, PCI Express and HDMI. While hardware is not expected to become available until around the end of 2010, it is worth noting as it may challenge the existence of USB 3.0 in the near future.
The table below summarises the facts for advising your customers appropriately.
| Specification |
Raw bandwidth (Mbit/s) |
Transfer Speed (MB/s) *1 |
Max Cable Length (m) |
Power Provided |
Devices per Channel |
| USB 2.0 |
480 |
60 *2 |
5 |
5V (500mA per port) |
127 (with hub) |
| USB 3.0 |
4,800 |
480 |
3 *3 |
5V (900mA per port) |
127 (with hub) |
| SATA 300 |
3,000 |
300 |
1 |
No |
1 |
| SATA 600 |
6,000 |
600 |
1 |
No |
1 |
| Lightpeak |
10,000 |
1,250 |
100 |
No *4 |
Multiple |
Notes: *1 After 8b/10b encoding / protocol overhead. *2 Actual real-world transfer rates are between 30 and 40MB/s. *3 3 metres is the limit for achieving max. bandwidth; otherwise cable assembly may be of any length. *4 Intel is working on bundling the optical fibre with copper wire so Light Peak can be used to power devices
While controllers enabling USB 3.0 and SATA revision 3.0 (integrated) in motherboards have been readily available for a while, most of the mainstream products on the market are not true, native implementations in the motherboard southbridge. They are typically implemented using third party controllers connected via the PCI-Express bus and this results in shared PCIe bandwidth or in the case of high-end motherboards, PCIe switching. AMD is the first to include SATA 6Gb/s support in its latest SB850 southbridge and Compucon's AMD-based workstations have been refreshed with this latest chipset. Intel has not yet implemented any of these technologies in their currently available chipsets (H57, P55, X58). Feel free to contact the editor for further information as desired.
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Supermicro New Zealand
Managed by Compucon New Zealand
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