Serial ATA Hard Drive Info

ATA Serial standard is a simplified packet switching network between a motherboard or
computer backplane and a disk drive.  It employs balanced voltage (differential) amplifiers
and four wires/two pairs (transmission line) to connect transmitters to receivers

Serial ATA (SATA) interface uses thin cables and simple connectors. Slim 7-conductor
wires replace the 80-conductor flat ribbon cables required by current hard disks, and the
standard includes a new power connector. The data connector and power connectors
are joined into a single unit for easy installation of new hard disks. The connectors are
key slotted to aid correct insertion.

 



Serial ATA data connector (left) and power connector (right)
 



ATA/100 Drive (top) and SATA Drive (bottom)

Parellel ATA and Serial ATA Cables

ATA/100 Drive (top) and SATA Drive (bottom)

 
Here are some brief highlights of this recent technology:
 
  • Scalable performance… Three stages over ten years… Starts at 1.5 Gigabits per second, then 3 Gbps, and ultimately 6 Gbps (six times faster than the current ATA/100 standard).  These numbers are right in the spec.
  • 100% software compatible with current operating systems and does not require any new drivers/changes to existing operating systems.
  • Primarily for inside-the-box drive connections.  Maximum cable length is 1 meter.  No cameras/scanners/printers.
  • Supports all ATA and ATAPI devices, including CDs, DVDs, tape
    devices, high capacity removable devices, zip drives, and CD-RWs.
  • Drives can be attached by cable or plugged directly into backplanes.
  • More reliable connectors with smaller plugs and a lower pin-count.
  • Plugs are blind mated (can plug them in blindfolded without making an error).
  • No drive jumpers or terminators, one drive per cable, Plug ‘n Play (Prey?).
  • Drives can be hot plugged—installed with the computer on.
  • Smaller cables (thin, flexible) that are simple to route and install.  The data cable has 4 conductors.
  • Smaller cables will allow much better case ventilation (and access/visibility).
  • Less complex trace runs on motherboards; will permit smaller motherboards.
  • ATA Serial interface to be incorporated into the motherboard chipsets.
  • Favorable (low) voltages and efficient power delivery.
  • Power management and power consumption suitable for mobile use.
  • Light protocol minimizes overhead latencies.
  • Asynchronous only (no isochronous requirements).
  • No peer-peer transfer support (to/from host only).
  • Provides support for 1st party DMA access to the host
     

When will Serial ATA infrastructure products be shipping in volume?
Individual vendors will best be able to advise on product plans. However, hard disk drives, cables, enclosures, and controllers are expected to be available to OEM and channel customers in 2002, with enterprise system vendors shipping platforms with Serial ATA storage by the second half of the year.

Where is Serial ATA positioned relative to other interface technologies?
Serial ATA technology provides a new serial interconnect designed to change the way vendors develop storage systems. The first deployments, where price is an important issue, are intended for entry-level servers and network-attached storage. As the infrastructure continues to develop, Serial ATA will penetrate into higher-end servers and more complex storage systems.

What is the long-term road map for Serial ATA?
Serial ATA defines a roadmap starting at 1.5 gigabits per second (equivalent to a data rate of 150MB/s) and migrating to 3.0 gigabits per second (300 MB/s), then to 6.0 gigabits per second (600 MB/s). This roadmap supports up to 10 years of storage evolution, based on historical trends.

How does Serial ATA handle backward compatibility issues?
Serial ATA supports legacy drivers for Parallel ATA. OEMs can deploy Serial ATA, today, using existing parallel ATA drivers. Vendors intend to supply bridges for parallel-to-serial conversion for legacy devices.

Are there any known interoperability issues with Serial ATA?
One of the primary requirements of the Serial ATA 1.0 specification was to maintain backward compatibility with existing operating system drivers to eliminate incompatibility issues.

How will operating systems handle Serial ATA?
Because of the legacy support inherent in the specification, operating support will be simplified. The Serial ATA specification allows for additional features to be added to applications. Additional features will be subject to normal driver validation processes.

How does the end-user benefit from using Serial ATA technology in servers and NAS?
The end-user will benefit from lower cost, higher performance (via increased speed and scalability), and easier configuration. Serial ATA allows for higher performance while using existing, proven features such as 3.5" disk drives. Configuration of Serial ATA devices will eliminate many of today's requirements for jumpers and settings.

How does the system vendor benefit from using Serial ATA technology in servers and NAS?
Benefits for the OEM:

  • Easier configuration and design with cables that are thinner, have smaller connectors, and are simpler to route and install.
  • Ability to use HDD technology across multiple segments such as desktops, entry and midrange servers, and networked storage.
  • Easier training for Sales and Tech Support staff.
  • Improved silicon design with lower voltage that will ease current design requirements in Parallel ATA Compatibility with today's software that will enable Serial ATA to run on the new architecture without modification.