Disk interface and disk Scan

Hard Disk interfaces include four types: IDE, SATA, SCSI, and fiber channel.

IDE

IDE is called "integrated drive electronics" in English, that is, "Integrated drive electronics ". It is intended to be a hard drive that integrates the "hard disk controller" with the "disk body. The integration of the disk and controller reduces the number and length of cables on the hard disk interface, enhances the reliability of data transmission, and makes it easier to manufacture the hard disk, hard Disk manufacturers do not need to worry about whether their hard disks are compatible with controllers produced by other manufacturers. It is more convenient for users to install hard disks. Since its birth, IDE has been continuously developing and its performance has been continuously improved. It features low price and strong compatibility, this makes it an irreplaceable position for other types of hard disks. For example, ATA, ultra ata, DMA, ultra DMA, and other interfaces all belong to the IDE hard disk.

IDE Interface

SCSI
SCSI is called the "small computer system interface" (a small computer system interface). It is a completely different interface from IDE (ATA). Ide interface is a standard interface of a general PC, SCSI is not an interface specially designed for hard disks, but a high-speed data transmission technology widely used on minicomputers. The SCSI interface has the advantages of wide application range, multi-task, high bandwidth, low CPU usage, and hot swapping. However, the high price makes it difficult to popularize like an IDE hard disk, therefore, SCSI hard disks are mainly used in medium and high-end servers and high-end workstations.

SCSI interface

SATA
A hard disk using the SATA (Serial ATA) port is also called a serial hard disk, which is a trend of PC hard disks in the future. In 2001, the Serial ATA committee, composed of Intel, APT, Dell, IBM, Seagate, and Alto, formally established the Serial ATA 1.0 specification. In 2002, although Serial ATA-related devices have not yet been officially listed, the Serial ATA Committee has established the Serial ATA 2.0 specification first. Serial ATA adopts the serial connection mode, and the Serial ATA bus uses embedded clock signals to provide better error correction capabilities. The biggest difference between the Serial ATA bus and the Serial ATA bus is the ability to transmit commands (not just data) check. If an error is found, it will be automatically corrected, which greatly improves the reliability of data transmission. The serial interface also has the advantages of simple structure and supports hot swapping.
Serial hard drive is a new type of hard drive interface that is completely different from parallel ata. It is well known for its serial transmission of data. Compared with parallel ata, it has many advantages. First, Serial ATA transmits data in a continuous serial mode, and only one bit of data is transmitted at a time. This reduces the number of SATA interface pins, reduces the number of connection cables, and increases the efficiency. In fact, Serial ATA can do all the work with only four pins, which are used to connect cables, Connect ground wires, send data, and receive data respectively, in addition, such an architecture can reduce system energy consumption and system complexity. Second, 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/s, which is more advanced than the latest parallel ATA (ATA/133) the maximum data transmission rate of up to 133 Mb/s is high, while the data transmission rate of 2.0 in Serial ATA will reach 300 MB/S. In the end, Sata will achieve the highest data transmission rate of 600 Mb/s.

SATA interface

Fiber Channel
The English spelling of the fiber channel is the fiber channel. Like the SCSI interface, the fiber channel was originally not an interface technology designed for hard disks, but was specially designed for network systems, but with the speed requirements of the storage system, it is gradually applied to the hard disk system. The Optical Fiber Channel hard drive is developed to improve the speed and flexibility of the Multi-disk storage system. Its appearance greatly improves the communication speed of the Multi-disk system. The main features of Fiber Channel include hot swapping, high-speed bandwidth, remote connection, and a large number of connected devices.
Fiber Channel is designed for multiple hard drive systems like servers, it can meet the high data transmission rate requirements of high-end workstations, servers, mass storage sub-networks, and peripherals for Bidirectional and serial data communication through hubs, switches, and point-to-point connections.

Optical Fiber Channel disk interface Diagram

In disk interface technology

The IDE interface is also called the PATA interface, that is, parallel ATA (parallel transmission ATA ). ATA is advanced technology attachment, which is an additional advanced technology.

ATA interfaces from birth to now have a total of 7 different versions, ATA-1 (IDE) Speed 3.3 Mb/s, ATA-2 (Eide enhanced IDE/fast ATA) Speed 16.6 Mb/s, ATA-3 (FastATA-2) speed 16.6 Mb/s, ATA-4 (ata33) Speed 33.3 Mb/s, ATA-5 (ata66) Speed 66.6 Mb/s, ATA-6 (ata100) speed 100 Mb/s, ATA-7 (ata133) Speed 133 MB/S

IDE has three data transmission modes:

Pio mode, DMA mode (Direct Memory Access), ultra DMA mode

Two specifications are available in Sata.

Sata1.0

Sata2.0

SCSI has

SCSI-1

SCSI-2 (fast SCSI)

SCSI-3 (ultra SCSI)

Ultra 2 SCSI

Ultra 160 SCSI

Ultra 320 SCSI

Disk scanning methods include FCFS (first-in-first-out), sstf (Shortest Path First), scan (revolving scan), C-SCAN (one-way scan), look (Intelligent Monitor scan mode), C-LOOK (Intelligent Monitor one-way scanning mode)