What is SATA interface? What does SATA interface mean?

The full English name of SATA is: Serial ATA.

SATA is the abbreviation of Serial ATA. This is a new type of hard disk interface that is completely different from parallel ATA. It is named because it uses serial data transmission. The SATA bus uses an embedded clock signal and has a stronger error correction capability. Compared with the past, its biggest difference is that it can check the transmission instructions (not just the data). If errors are found, they will be automatically corrected, which greatly improves the reliability of data transmission. The serial interface also has the advantages of simple structure and hot-swap support.

Compared with parallel ATA, SATA has a relatively large advantage. First, Serial ATA transmits data in a continuous serial manner, and can use a higher operating frequency at a smaller bit width to increase the bandwidth of data transmission. Serial ATA only transmits 1 bit of data at a time, which can reduce the number of pins on the SATA interface, reduce the number of connecting cables, and increase efficiency. In fact, Serial ATA can complete all tasks with only four pins, which are used to connect cables, connect ground wires, send data, and receive data. At the same time, such an architecture can also reduce system energy consumption and reduce system complexity. Secondly, Serial ATA has a higher starting point and greater development potential. The data transfer rate defined by Serial ATA 1.0 can reach 150MB/sec, which is higher than the maximum data transfer rate of 133MB/sec that can be achieved by the current fastest parallel ATA (i.e. ATA/133), and the current SATA II data transfer rate is as high as 300MB/sec.

The Serial ATA specification is not only future-proof, but also retains a variety of backward compatibility methods, so there are no compatibility issues in use. In terms of hardware, the Serial ATA standard allows the use of converters to provide compatibility with parallel ATA devices. The converter can convert the parallel ATA signal from the motherboard into a serial signal that can be used by the Serial ATA hard disk. Currently, there are many such adapters/adapters on the market, which to some extent protects our original investment and reduces the cost of upgrading; in terms of software, Serial ATA and parallel ATA maintain software compatibility, which means that manufacturers do not have to rewrite any driver and operating system code to use Serial ATA.

In addition, Serial ATA wiring is much simpler than traditional Parallel ATA wiring, and it is easy to retract, which significantly improves the airflow and heat dissipation in the chassis. Moreover, unlike Parallel ATA, which is always trapped in the chassis, SATA hard disks are highly expandable and can be externalized. External cabinets (JBOD) not only provide better heat dissipation and plug-in functions, but also multiple connections to prevent single point failures; because the design of SATA and Fiber Channel is exactly the same, the transmission speed can be guaranteed by different channels, which is of great significance in server and network storage.

SATA II is developed on the basis of SATA. Its main feature is that the external transfer rate is further increased from SATA's 1.5Gbps (150MB/sec) to 3Gbps (300MB/sec). In addition, it also includes a series of technical features such as NCQ (Native Command Queuing), Port Multiplier, Staggered Spin-up, etc. A simple external transfer rate of 3Gbps is not true SATA II.

The key technologies of SATA II are the 3Gbps external transmission rate and NCQ technology. NCQ technology can optimize the execution order of hard disk instructions, avoiding the traditional hard disk mechanically moving the magnetic head to read and write different positions of the hard disk in the order of receiving instructions. On the contrary, it will sort the commands after receiving them, and the sorted magnetic heads will address them in a highly efficient order, thus avoiding the loss caused by repeated movement of the magnetic heads and extending the life of the hard disk. In addition, not all SATA hard disks can use NCQ technology. In addition to the hard disk itself supporting NCQ, the SATA controller of the motherboard chipset is also required to support NCQ. In addition, NCQ technology does not support FAT file system, but only supports NTFS file system.

Due to the confusion in the SATA device market, many SATA device providers have been abusing "SATA II" in their marketing. For example, some hard drives claiming to be "SATA II" only support 3Gbps but not NCQ, while some hard drives with only 1.5Gbps support NCQ. Therefore, SATA-IO (Serial ATA International Organization, formerly SATA Working Group) led by Seagate announced the SATA 2.5 specification, which includes most of the functions of the original SATA II - from 3Gbps and NCQ to staggered spin-up, hot plug, port multiplier and the newer eSATA (External SATA, external SATA interface) and so on.

It is worth noting that some motherboards that use an earlier south bridge chip that only supports 1.5Gbps (such as VIA VT8237 and NVIDIA nForce2 MCP-R/MCP-Gb) may not find the hard disk or display a blue screen when using a SATA II hard disk. However, most hard disk manufacturers have set a speed selection jumper on the hard disk to force the selection of 1.5Gbps or 3Gbps working mode (a few hard disk manufacturers use corresponding tool software to set it). As long as the hard disk is forced to be set to 1.5Gbps, the SATA II hard disk can still be used normally on the old motherboard.

When setting up RAID mode for SATA hard drives, you generally need to install the driver provided by the motherboard chipset manufacturer. However, there are a few older SATA RAID controllers that can form RAID without loading the driver in some Windows XP systems with the latest patches and integrated SATA RAID drivers.

SATA has many advantages over parallel ATA and will become a cheap alternative to parallel ATA. And the complete transition from parallel ATA to SATA is also the general trend, and it should only be a matter of time. Relevant manufacturers are also vigorously promoting the SATA interface. For example, Intel's ICH6 series south bridge chip supports 4 SATA interfaces from 2 compared to the ICH5 series south bridge chip, while the parallel ATA interface is reduced from 2 to 1; the ICH7 series south bridge further supports 4 SATA II interfaces; the next generation ICH8 series south bridge will support 6 SATA II interfaces and will completely abandon the parallel ATA interface; other motherboard chipset manufacturers have also begun to support the SATA II interface; currently, hard disks with SATA II interfaces have gradually become mainstream; other devices using SATA interfaces, such as SATA optical drives, have also appeared.

It is worth noting that, whether it is SATA or SATA II, it actually has little impact on hard disk performance. Because the bottleneck of hard disk performance is currently concentrated on the internal data transfer rate of the hard disk, which is determined by the internal mechanical structure of the hard disk, the hard disk storage technology, and the disk rotation speed. Even the current top 15,000 rpm SCSI hard disk has an internal data transfer rate of only about 80MB/sec, not to mention the ordinary 7,200 rpm desktop hard disk. Unless the data recording technology of the hard disk undergoes revolutionary changes, such as vertical recording technology, etc., the internal data transfer rate of the hard disk is difficult to achieve a leap forward. To put it bluntly, the current hard disk using ATA 100 is completely sufficient. The reason for using more advanced interface technology is that it can obtain higher burst transfer rates, support more features, be more convenient and easy to use, and have more development potential.