What is SATA (Serial ATA)?

Definition

Abbreviated from Serial Advanced Technology Attachment, SATA (Serial ATA) is a computer bus interface. Users use it to connect the computer’s host bus adapters to mass storage devices such as ATA hard drives, solid-state drives, etc.

SATA drives vary in speed and capacity. And the data transfer rate of the latest generation, SATA III, reaches 600MB/s bandwidth.

As the successor of the earlier PATA (Parallel ATA), SATA has become the leading interface for storage devices because of its solid transfer speed and excellent storage capacity.

Features

Hot Plug

The SATA specification requires hot plugging of the SATA device, which means that devices conforming to the specification can plugin or remove backboard connectors with power supplies or from backplate connectors. After insertion, the device works properly.

But this feature requires appropriate support at the host, device, and operating system levels. Typically, SATA devices meet the device-side hot-plugging requirements, and most SATA host adapters support this feature.

AHCI

Released and used by Intel, AHCI, abbreviated from The Advanced Host Controller Interface, has become the de-facto standard. It is an open host controller interface that allows the use of SATA’s advanced features, such as hotplug and native command queue (NCQ).

The SATA controller will typically operate in the “IDE emulation” mode if AHCI is not enabled on the motherboard and chipset. “IDE emulation” mode will not allow access to the device features that are not supported by the ATA (IDE) standard.

Revisions

The non-profit SATA-IO Industry Consortium writes the technical specifications for managing SATA device interfaces. The consortium has made some revisions to the SATA standards, which reflect the increase in data transfer rates.

SATA Revision 1.0

• Released on January 7, 2003, Revision 1.0 is the first-generation SATA interface. And it is now known as SATA 1.5 Gbit/s.
• It doesn’t support NCQ (Native Command Queuing).
• Revision 1.0 devices peak at a transfer rate of 1.5 Gbit/s. But considering the 8b/10b encoding overhead, its actual uncoded transfer rate is 1.2 Gbit/s (150 MB/s)

SATA Revision 2.0

• Released in April 2004, SATA revision 2.0 is the second-generation SATA interface and is backward compatible with SATA Revision 1.0 (SATA 1.5 Gbit/s).
• It was introduced to NCQ (Native Command Queuing).
• With a native transfer speed of 3.0 Gbit/s, SATA Revision 2.0 devices doubled the transfer speed to 3.2 Gbps.
• It was better developed in port selectors, multipliers port, and improved queuing.
• SATA Revision 2.5 was announced in August 2005, which consolidated the specification into a single document. And SATA Revision 2.6 was published in February 2007.

SATA Revision 3.0 

• As the third generation, the full SATA Revision 3.0 was released on May 27, 2009, and is backward compatible with Revision 1.0 and Revision 2.0.
• It operates at a native transfer rate of 6.0 Gbit/s, which is twice that of SATA Rev 2.0. And its maximum uncoded transfer rate reaches 4.8 Gbit/s (600 MB/s) considering 8b/10b encoding.
• To improve the quality of service for high-priority outages and video streaming, Revision 3.0 enhanced a lot in its functions.
• SATA Revision 3.1 was released in July 2011, while Revision 3.2 in August 2013, Revision 3.3 in February 2016, and Revision 3.4 in June 2018. All the above have multiple changes in many features.

Advantages

Compared with PATA, SATA enjoys many advantages.

• The SATA is the current standard, but the PATA is obsolete.
• The SATA is equipped with NCQ (Native Command Queuing).
• SATA transfers data much faster than PATA. The transfer rate of the slowest SATA version reached 150MB/s.
• SATA drives enjoy a hot-plugging feature so they can be inserted and removed without shutting down the computer.

Conclusion

After reading this post, you may have a general idea about SATA (Serial ATA) in its definition, features, revisions, as well as its advantages.