The hard disk interface is a connection between the hard disk and the host system, and the function is to transfer data between the hard disk cache and host memory. Different hard disk interfaces determine the connection speed between the hard disk and the computer, in the entire system, the advantages and disadvantages of the hard disk interface directly affect the program running and the system performance is good. From the overall point of view, the hard disk interface is divided into four types of IDE, SATA, SCSI, and Fiber Channel. The IDE interface hard disk is used in home products, and is also partially applied to the server. The hard disk of the SCSI interface is mainly applied to the server market, while Fiber Channel Only on high-end servers, prices are expensive. SATA is a new-ranging hard disk interface type, which is also out of the market popularization phase, has a wide prospect in the home market. Under the big category of IDE and SCSI, there can be a variety of specific interface types, and each has different technical specifications, with different transmission speeds, such as ATA100 and SATA; Ultra160 SCSI and Ultra320 SCSI represent a specific specifically The hard disk interface, each speed difference is also large.
The English "Integrated Drive Electronics", "Electronic Integrated Drive", which integrates the hard drive that integrates the "hard disk controller" with "tray". The practice of integrating the disk and the controller reduces the number of hard drive interfaces and length, the reliability of data transmission is enhanced, and the hard disk is made easier, because hard disk manufacturers don't need to worry about whether their hard drive is Controller produced with other vendors. For users, hard drives are more convenient. The interface technology of IDE has been continuously developed, and its performance is constantly increasing. It has the characteristics of low prices and strong compatibility. It is not alternative to other types of hard drives.
IDE represents a type of hard disk, but in actual applications, people are also accustomed to the first IDE type hard disk ATA-1 with IDE, this type of interface has been eliminated with the development of interface technology, and After the development of more types of hard disk interfaces, such as ATA, ULTRA ATA, DMA, ULTRA DMA, and other interfaces belong to the IDE hard drive.
SCSI SCSI's English is a "Small Computer System Interface" (small computer system interface), which is an interface with Ide (ATA). The IDE interface is a standard interface of ordinary PC, and SCSI is not specifically for hard disk design. It is a high speed data transmission technology that is widely used in small machines. The SCSI interface has the advantages of wide application range, multitasking, low bandwidth, low CPU, and hot plug, high prices make it difficult to spread as the IDE hard drive, so the SCSI hard drive is mainly applied to medium and high-end servers. And high-end workstations.
The English spelling of Fiber Channel Fiber Channel is FIBRE CHANNEL, and the Fiber Channel is not the interface technology developed by the hard disk. It is designed for network systems, but with the speed demand for speed, it is gradually applied. In the hard disk system. Fiber Channel hard drives are developed to improve the speed and flexibility of multi-hard disk storage systems, which greatly enhances the communication speed of the multi-hard disk system. The main features of the Fiber Channel are: hot plug, high-speed bandwidth, remote connection, large number of connecting devices.
Fiber Channel is designed to meet high-end workstations, servers, mass storage subsystems, and external, serial data communications, etc. Requirements for transmission rates.
SATA uses the hard drive of the SATA (Serial ATA) and is called a serial hard disk, which is the trend of the future PC hard drive. In 2001, the Serial ATA Committee consisting of Intel, Apt, Dell, IBM, Seagate, Miao Tuo officially established Serial ATA 1.0 specification, 2002, although serial ATA's related equipment has not been officially launched, but Serial The ATA Committee has first established the Serial ATA 2.0 specification. Serial ATA uses a serial connection method, serial ATA bus uses embedded clock signals, with stronger error correction capability, with the greatest difference in conventional differences in detecting transmission instructions (not just data), if It is found that the error 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-swappable. SATA interface details: SATA is the abbreviation of Serial ATA, that is, serial ATA. This is a new type of hard disk interface that is completely different from parallel ATA, which is named by serialization. The SATA bus uses an embedded clock signal that has stronger error correction capabilities, which has a maximum difference compared to the past is to check the transfer command (not just data). If the error is automatically corrected, this is very big The degree increases the reliability of data transmission. The serial interface also has the advantages of simple structure and supporting hot-swappable.
SATA has a relatively large advantage over parallel ATA. First, the Serial ATA transmits data in a continuous serial manner, which can use a higher operating frequency to increase the bandwidth of the data transmission at a few bit width. Serial ATA will only transfer 1 bit of data at a time, which reduces the number of pins of the SATA interface, so that the number of connecting cables becomes less, and efficiency will be higher. In fact, Serial ATA can complete all work only with four pins, separately for connecting cables, connecting ground, sending data, and receiving data, while such architectures can reduce system energy consumption and reduce system complexity. Secondly, Serial ATA has a higher starting point, greater development potential, and the data transfer rate defined by Serial ATA 1.0 can reach 150MB / sec, which can reach 133MB / sec to the current parallel ATA (ie ATA / 133). The data transfer rate is also high, and the data transfer rate of the released Serial ATA 2.0 will reach 300MB / sec, and final Serial ATA 3.0 will implement the highest data transfer rate of 600MB / sec.
It is necessary to explain the data transfer rate of Serial ATA here. For serial communication, the data transfer rate refers to the actual bit rate of serial interface data transmission. The transmission rate of Serial ATA 1.0 is 1.5Gbps, and the transmission rate of Serial ATA 2.0 is 3.0Gbps. Like other high-speed serial interfaces, the Serial ATA interface also uses a set of encoding mechanisms to ensure data stream characteristics, which encodes the 8-bit data (ie, 1byte = 8bit) included in each byte into 10 Data (ie 1byte = 10bit), in this way, the serial data stream of the Serial ATA interface contains 10-bit data, and the encoded Serial ATA transmission rate is corresponding to the actual transmission rate of the Serial ATA accordingly. One of them, so 1.5Gbps = 150MB / sec, and 3.0Gbps = 300MB / sec.
SATA's physical design can be said to be a Fibre Channel (Fiber Channel) as Blueme, so use four-core wiring; the demand voltage is greatly reduced to 250mV (up to 500mV), more than 5V of the traditional parallel ATA interface! Therefore, manufacturers can add advanced hard disk functions to the Serial ATA hard drive, such as hot swapping, and so on. More importantly, in the form of connection, in addition to the traditional point-to-point form, SATA also supports "stars" connection, so you can provide a design convenience to the advanced application such as RAID; In the use of the SATA's host bus adapter (HBA, Host Bus Adapter), like a switch on the network, you can implement the form of channels and each hard disk communication, that is, each SATA hard disk monoped a transmission channel, so There is no problem with main / slave control like parallel ATA. The Serial ATA specification is not only based in the future, but also reserves a variety of backward compatible methods, there is no compatibility with compatibility. In terms of hardware, the SERIAL ATA standard allows the use of converters to provide compatibility with parallel ATA devices. The converter can convert parallel ATA signals from the motherboard into serial ATA hard drives that can be used by serial ATA hard drives. There are currently a variety of such classes. The transfer card / adapter is listed, which protects our original investment to some extent, reduces upgrade costs; in software, Serial ATA and parallel ATA maintain software compatibility, which means that manufacturers don't have to Rewrite any drivers and operating system code for using Serial ATA.
In addition, the Serial ATA wiring is much simpler, and it is easy to place, which is significantly improved to the airflow and heat dissipation in the chassis. Moreover, the SATA hard disk is different from parallel ATAs that are always trapped in the chassis, the expansion is very strong, that is, external, external cabinets (JBOD) can not only provide better heat dissipation and plug, and more Connection to prevent single point failure; due to the designs of SATA and Fiber Channels, the transmission speed can be guaranteed by different channels, which is of great significance in servers and network storage.
Serial ATA can be more advantageous than ATA, which will become a cheap alternative to parallel ATA. And transition from parallel ATA to Serial ATA is also a general trend. It should be just a matter of time. Related manufacturers have also vigorously promote SATA interface, such as Intel's ICH6 Series South Bridge chip compared to ICH5 series Nanqiao chip, the supported SATA interface increases from 2 to 4, and parallel ATA interfaces are reduced from 2 to 1 NVIDIA's NFORCE4 series chipset already supports SATA II Serial ATA 2.0, and Samsung has developed a new generation of SATA II interface hard drives with Marvell 88i6525 SOC chip and will be launched in early 2005.
