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Ultra320:
Next Generation SCSI Performance |
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This is twice as fast as the previous Ultra160 standard and also provides other features to improve reliability, performance, and ease of use. Of course Ultra320 is backwards compatible with previous SCSI standards/device and there are Ultra320 RAID Controllers for super-fast and reliable fault-tolerant data storage. Ultra320 is not just the next level in the SCSI standard, but a necessary step for the future growth of storage technology and storage subsystems. With 10K-RPM and 15K-RPM SCSI Hard drives providing extremely fast read/write data access and burst data speeds, a faster SCSI Bus interface is needed when using multiple drives (remember that SCSI drives share the same cable/bus per controller, so when using multiple drives bottlenecks can occur). The increased bandwidth of Ultra320 is a solution to this problem. It is also the perfect for the high-volume demands of applications such as databases, streaming digital audio and video, video editing, corporate network servers, and RAID configurations. See chart below for details on Ultra320's advanced features. |
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| Features of Ultra320 | Description / Information |
| Double Transfer Speed | Double the transfer rate of Ultra160 (burst-speed) to 320MB/sec. |
| Quick Arbitration and Selection (QAS) | A method for reducing the overhead of control release on the SCSI bus from one device to another. Reduces command overhead and maximizes bus utilization. |
| Read and Write Data Streaming | Minimizes the overhead of data transfer by allowing the target to send one data stream packet (LUN Q-TAG) followed by multiple data packets instead of one LQ packet for each data packet. |
| Flow Control | Allows the initiator to optimize its pre-fetching of data during writes and flushing of data FIFOs during reads. |
| Training Pattern | Sends a training pattern test signal to measure the imbalances in the SCSI bus (signal skew or delays) and generate corrections to better utilize the data. |
| Pre-compensation | The higher speed of Ultra320 causes greater signal attenuation and problems with ISI (Inter-symbol Interference) which causes bit-distortion due to the SCSI bus being charged when the signal stays at one voltage level for a long period of time. Pre-compensation addresses this problem at the transmission side by reducing the signal's maximum drive level when a stream of zeroes or ones occurs (no transition). |
| Adjustable Active Filter (AAF) | AAF also addresses the above problems with attenuation and ISI on the receiving side of the SCSI bus by increasing the signal-to-noise ratio using a method for filtering out frequencies higher than the maximum Ultra320 SCSI signal frequency. |
| Packetized SCSI | Improved protocol to encapsulate command information into packets and transfer them synchronously at maximum negotiated rate (i.e. 320 MB/sec). |
| Cyclic Redundancy Check (CRC) | CRC is an algorithm that provides improved data protection for the parallel SCSI bus performing error checking on transmitted bytes. |
| Other Information | Description / Information |
| Ultra320 Cards + 64-bit PCI-X Slots | The use of the 64-bit PCI-X bus combined with with Ultra320 allows for maximum bandwidth usage with multiple drives (thus preventing bottlenecks). PCI-X can deliver up to 1064MB/second (64-bit @ 133Mhz). |
| Ultra 320 Cables | Recommended to use Ultra320 Flat or Rounded cables. Adaptec recommends rounded-shielded cables to minimize data loss due to signal attenuation. See below for more info.. |
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Ultra320 Products |
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Ultra320Drives: Maxtor, Seagate, IBM |
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Ultra320
Barebone Systems: Supermicro already has systems with Ultra320 embedded SCSI controllers and
hot-swap drive bays. |
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| Ultra320 LVD CABLES: Although backwards compatible with Ultra160 (SPI-3) SCSI LVD cables it is recommended to use Ultra320 (SPI-4) rated "Flat and Twist" or "Rounded-Shielded" LVD cables. If you use Ultra160 LVD cables you risk data-corruption or reducing the bus speed in half. The flat cables are fine for shorter distances within cases, but for longer lengths or where extra electromagnetic "noise" (EMI) may occur, a rounded-shielded cable is best. | |
The seventh
generation SCSI I/O Bus Interface has recently hit the market.
This
specification is called Ultra320 and has
maximum transfer rate 320MB/second.
