The ATA standard define a simple, inexpensive method for attaching disk drive to host system and was one of the first attempts at developing a storage standard. The original ATA standard (ATA-1) was formally defined in 1993 and has gone through five major revisions up to the current standard, ATA-6. The standard defines a simple method to connect high-volume disk devices with internal controllers to host systems. It incorporates all layers of the protocol in a single standard, from the 80-pin parallel connector to the commands recognized by the disk drives.
In the late 1990s, many companies started to recognize that the existing ATA standard had many limitations that would prevent it from scaling up to support future generation systems. The biggest issues were :
Serial ATA addresses the limitations of the ATA standard by allowing the commands to be sent over a serial cable connection with significantly fewer wires, which greatly reduces the EMI and allows much higher data speed to be obtained. It also reduces the complexity of the cabling and reduces the voltage requirements from 5 volts to 3.3 volts. These changes allow first version of the serial ATA specification to provide 150 MB/s throughput, compared with parallel ATA’s limitation of 133 MB/s. The serial ATA-2 standard, release in 2003, increase this to over 300 MB/s and even more advanced versions are under development. This ensures that Serial ATA drives can provide significantly higher levels of performance while maintaining the low coast per megabyte associated with ATA disk drives.
Another advantage to Serial ATA specification is reliability and availability. There are three primary reliability/availability benefits inherent in the basic SATA specification:
*from http://www.emc.com
In the late 1990s, many companies started to recognize that the existing ATA standard had many limitations that would prevent it from scaling up to support future generation systems. The biggest issues were :
- It required a 5-volt signal, while many newer integrated circuits were moving to a 3.3-volt standard.
- The cable require 80 wires, making them expensive and subject to electronic magnetic interface (EMI). This EMI limited the maximum speed that could be used with a parallel ATA interface and reduce reliability.
- In 2000, a group of companies announced the formation of the SATA Working Group to explore the development of a next-generation serial ATA standard.
Serial ATA addresses the limitations of the ATA standard by allowing the commands to be sent over a serial cable connection with significantly fewer wires, which greatly reduces the EMI and allows much higher data speed to be obtained. It also reduces the complexity of the cabling and reduces the voltage requirements from 5 volts to 3.3 volts. These changes allow first version of the serial ATA specification to provide 150 MB/s throughput, compared with parallel ATA’s limitation of 133 MB/s. The serial ATA-2 standard, release in 2003, increase this to over 300 MB/s and even more advanced versions are under development. This ensures that Serial ATA drives can provide significantly higher levels of performance while maintaining the low coast per megabyte associated with ATA disk drives.
Another advantage to Serial ATA specification is reliability and availability. There are three primary reliability/availability benefits inherent in the basic SATA specification:
- Simplified cabling
- Integrated Cyclic Redundancy Checks (CRC)
- Hot-swappability
*from http://www.emc.com