SATA disk drive FAQ
Background
Serial ATA is 100% software compatible with today's ATA, but has a much lower pin count, enabling thinner, more flexible cables. APT, Dell, IBM, Intel, Maxtor, and Seagate are jointly leading this initiative, with broad industry support from over 80 companies that make up the Serial ATA Working Group. Serial ATA will allow the performance of internal storage devices to continue to increase unabated for generations to come.
Frequently Asked Questions
- What is Serial ATA?
- Why is Serial ATA being developed?
- What are the enduser benefits of Serial ATA?
- Disc drive data rates have not exceeded ATA100 limits yet, why should I switch to Serial ATA?
- What do I need to integrate Serial ATA?
- Are there differences in Serial ATA solutions by different HDD vendors?
- Will I see a performance difference in Serial ATA drives?
- How does Serial ATA and Serial Attached SCSI work together?
What is Serial ATA?
Serial ATA (Advanced Technology Architecture) is an interface for desktop system drives that is used to connect hard drives and other peripherals to a PC. It is the evolutionary replacement for the Parallel ATA (PATA) physical storage interface.
Why is Serial ATA being developed?
Serial ATA is scalable and will allow future enhancements to the computing platform. Parallel ATA has been a solid interface allowing performance scalability and reliable data tranmission but drive rates continue to climb and system designs continue to demand more flexibility and robustness from components. Serial ATA will allow the performance and growth to continue without adding costs and extra ordinary means to achieve the requirements.
What are the end-user benefits of Serial ATA?
Overall system reliability improvements to airflow and thermal dynamics, as well as, easier installations and upgrades.
Disc drive data rates have not exceeded ATA100 limits yet, why should I switch to Serial ATA?
The maximum internal data rate on an IDE disc drive today is ~133MB/sec. That data path in PATA has reached its limit. Serial ATA allows disc drives to continue to offer performance and reliability at cost parity to Parallel ATA. In addition, Serial ATA interface requires less voltage meaning better power consumption and management in both desktop and mobile applications. The thinner cable allows for flexible designs and improved airflow in smaller form-factors.
What do I need to integrate Serial ATA?
The Serial ATA adoption will first take place with the introduction of Serial ATA drives and Host Bus Adapters in Mid to late 2002. By Q1 of 2003, you will start to see Serial ATA motherboards integrated into desktop systems. One of the main objectives of the Serial ATA working group was that Serial ATA would not require any software changes, Serial ATA basically is 100% software compatible - no changes to current operating systems or applications. All you need is a Serial ATA drive, Serial ATA HBA and Serial ATA interface cable and power adapter.
Are there differences in Serial ATA solutions by different HDD vendors?
Yes, there are two main methods for establishing the Serial ATA interface on the disc drives and hosts, "native" and "bridge".
One method called "native", allows maximum throughput, bypassing the legacy Task File reads and writes, as well as the limitation of 133MB/sec for Ultra DMA Mode 6 transfers to enable the maximum 150MB/sec transfer rate for first-generation Serial ATA devices.
A bridge solution enables the adaptation of a parallel device to the Serial ATA interface. Because the Serial ATA information flow occurs at 1.5Gbps, it is not always possible for the Link state machines to keep up when using a bridge device. The link layers on a bridged system must incorporate buffering to allow for throttling the interface if one side gets behind.
Will I see a performance difference in Serial ATA drives?
You may see a 1 - 5% performance increase from a PATA drive to a Serial drive but the main performance benefit is in the long run when because of Serial ATA, the hard drive through put will not bottle neck the system performance. In the mean time, system integrators and OEMs will enjoy a big reduction in assembly time and reductions in handling damage due to connector and pin issues.
How does Serial ATA and Serial Attached SCSI work together?
Serial Attached SCSI compliments Serial ATA by adding device addressing, and offers higher reliability and data availability services, along with logical SCSI compatibility. It will continue to enhance these metrics as the specification evolves, including increased device support and better cabling distances. Serial ATA is targeted at cost-sensitive non-mission critical server and storage environments. Most importantly, these are complementary technologies based on a universal interconnect, where Serial Attached SCSI customers can choose to deploy cost-effective Serial ATA in a Serial Attached SCSI environment.
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