What is SATA interface?
Time：2018-12-21Views：3285 Author：Yixinying
SATA Interface: SATA is the abbreviation of Serial ATA, namely serial ATA. This is a new type of hard disk interface entirely different from parallel ATA, named for its serial transmission of data. SATA bus uses embedded clock signal and has stronger error correction ability. Compared with the past, SATA bus has the greatest difference in that it can check the transmission instructions (not only 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 supporting hot swap.
Compared with parallel ATA, SATA has more advantages. Firstly, Serial ATA transmits data in serial mode, and can use higher frequency to improve the bandwidth of data transmission with less bit width. Serial ATA can only transmit one bit of data at a time, which can reduce the number of pins in SATA interface, reduce the number of connecting cables and improve efficiency. In fact, Serial ATA can do all the work with only four pins, which are used to connect cables, ground wires, send data and receive data respectively. At the same time, this architecture can reduce system energy consumption and reduce system complexity.Secondly, Serial ATA has a higher starting point and greater development potential. The data transmission rate defined by Serial ATA 1.0 can reach 150 MB/sec, which is higher than the current maximum data transmission rate of 133 MB/sec achieved by the most block parallel ATA (ATA/133), while the data transmission rate of Serial ATA 2.0 released will reach 300 MB/sec, and ultimately Serial ATA 3.0 will achieve the maximum data transmission rate of 600 MB/sec.
It is necessary to explain the data transmission rate of Serial ATA. As far as serial communication is concerned, data transmission rate refers to the actual bit rate of serial interface data transmission, the transmission rate of Serial ATA 1.0 is 1.5 Gbps, and the transmission rate of Serial ATA 2.0 is 3.0 Gbps. Like other high-speed serial interfaces, the Serial ATA interface uses a coding mechanism to ensure the characteristics of data streams.This encoding mechanism encodes 8 bits of data (i.e. 1Byte = 8bit) into 10 bits (i.e. 1Byte = 10bit). Thus, the serial data stream per byte of the Serial ATA interface contains 10 bits of data. The encoded Serial ATA transmission rate correspondingly changes to one tenth of the actual transmission rate of the Serial ATA, so 1.5Gbps = 150MB/sec, and 3.0Gbps = 300MB/sec.
The physical design of SATA can be said to be based on Fibre Channel (Fiber Channel), so it uses four-core wiring; the required voltage is greatly reduced to 250 mV (up to 500 mV), which is 20 times less than the traditional parallel ATA interface 5V! Therefore, the manufacturer can attach advanced hard disk functions such as Hot Swapping to Serial ATA hard disk. More importantly, in connection form, besides the traditional Point-to-Point form, SATA also supports "star" connection, which can provide design convenience for advanced applications such as RAID.In practical use, SATA host bus adapter (HBA, Host Bus adapter) can communicate with each single hard disk in the form of channels like switches on the network, that is, each SATA hard disk has a transmission channel, so there is no master/slave control problem like parallel ATA.
Serial ATA specification is not only based on the future, but also retains a variety of backward compatibility methods. There is no compatibility problem in use. In terms of hardware, Serial ATA standard allows converters to provide compatibility with parallel ATA devices. Converters can convert parallel ATA signals from motherboard into serial signals that Serial ATA hard disk can use. At present, there are many kinds of such adapters/adapters on the market, which to some extent protects our original investment and reduces the upgrade cost. Erial ATA and parallel ATA maintain software compatibility, which means that vendors do not have to rewrite any driver and operating system code to use Serial ATA at all.
In addition, Serial ATA wiring is much simpler than the traditional parallel ATA wiring, and it is easy to retrieve and release, which improves the airflow and heat dissipation in the chassis. Moreover, the SATA hard disk is different from the parallel ATA which is always trapped in the chassis. It has strong expansibility, that is to say, the external cabinet (JBOD) can 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 optical fiber channel is the same, the transmission speed can be guaranteed by different channels, which are in the server. And network storage is of great significance.
Serial ATA has many advantages over parallel ATA and will become a cheap alternative to parallel ATA. And the transition from parallel ATA to Serial ATA is also the general trend. It should be only a matter of time. Relevant manufacturers are also vigorously promoting SATA interfaces, such as Intel's ICH6 series Nanqiao chips, compared with ICH5 series Nanqiao chips, which support four SATA interfaces, while the parallel ATA interface is reduced from two to one; nVidia's nForce4 series chipsets have supported SATA II, Serial ATA 2.0, and Samsung has adopted Marvell 88i6525 SOC chips to develop a new generation of SATA. II interface hard disk, which will be launched in early 2005.
