hard disk lists
Hard Drive Permanent Disk Eraser - Wipe Your Data Secuely per IT Industry Standard Utility - Live Bootable Boot USB Flash Thumb Drive USB-C
Seagate Portable 1TB External Hard Drive HDD – USB 3.0 for PC, Mac, PlayStation, & Xbox, 1-Year Rescue Service (STGX1000400) , Black
Toshiba Canvio Basics 1TB Portable External Hard Drive USB 3.0, Black - HDTB510XK3AA
Seagate Portable 1TB External Hard Drive HDD USB 3.0 for PC Laptop and Mac (STGX1000400) & Amazon Basics External Hard Drive Portable Carrying Case
ADATA AHV620S-1TU3-CBK 1TB HV620S Slim External Hard Drive 2.5 USB 3.1 11.5mm Thick Black - (Storage > External Hard Drives)
Hard disk Overview
The development history of hard disk
In 1956, the world's first hard disk was born, it was built by IBM, called the 350RAMAC.
The disk has a diameter of 24 inches and 50 discs, weighs hundreds of kilograms, and is the size of two refrigerators, but its storage capacity is only 5MB.
In 1973, the Winchester hard drive was born.
In 1980, the first Gigabyte capacity hard disk and the first home hard disk were introduced. In the late 1980s, IBM introduced the Magneto Resistive (MR) technology, a new type of magnetic head that uses magnetic induction to write and magnetoresistive to read, which greatly improves the sensitivity of the magnetic head and greatly improves the work efficiency of the hard disk. At the same time, the disk storage density is also dozens of times higher than the previous 20Mbpsi (bit/ square inch), laying the foundation for a huge increase in hard disk capacity.
In 1991, hard disk technology made a huge breakthrough. Since then, the development of hard drives has accelerated, and the storage capacity has also increased.
The specifications of the hard disk
The specifications of hard disks mainly include the following aspects:
Type:
Hard drives can be divided into mechanical hard drives (HDD),solid state drives (SSD), and hybrid hard drives (SSHD).
The mechanical hard disk is written to the disk by means of an electromagnetic current that changes the polarity of the head very close to the magnetic surface. Its advantage is that the price is cheap, the capacity is generally greater than 1T, and the long-term storage of data is safer than the solid state disk, but the disadvantage is that the read and write data is slow, the volume is generally larger, the weight is heavier, and the noise of the higher the speed of the hard disk is greater.
A solid-state drive is a computer storage device that uses primarily NAND Flash as its permanent memory. Its advantages are fast reading speed, small size, light weight, strong drop resistance, no noise, but the disadvantage is that the price is high, and once a flash memory fails, the data of the entire hard disk will be lost.
Interface: The interface of mechanical hard disk mainly includes SATA, PATA (IDE), SCIS and SAS, of which SATA and PATA (IDE) interface is mainly used for personal computers, while SCIS and SAS interface is mainly used for servers. SSD interfaces are mainly SATA, M.2, PCI Express and U2, of which SATA interface hard disks are mostly 2.5 inches, while M.2 interface hard disks are 2080, 2042, 2060 and 20110 specifications.
Size: The dimensions of the hard disk include 5.25 inches, 3.5 inches, 2.5 inches, and 1.8 inches. Among them, the 5.25-inch hard disk has been retired from the market, the 3.5-inch hard disk is often used in desktop computers, the speed is more than 7,200 RPM, and the 2.5-inch hard disk is often used in notebooks, the speed is more than 5,400 RPM.
The major brands
Western Digital Corporation (WD) : Western Digital Corporation (Western Digital Corporation) is a world-renowned hard disk drive manufacturer headquartered in California, USA.
Seagate: Seagate Technology is a leading global provider of hard disk and storage solutions, founded in 1979 and headquartered in California.
Toshiba Corporation (Toshiba Corporation) is a Japanese diversified technology company founded in 1875 and headquartered in Tokyo.
Hitachi Global Storage Technologies (HGST) is a leading global hard drive manufacturer, founded in 2003 by the merger of Hitachi Manufacturing and IBM's hard drive division, headquartered in California, USA.
In addition, there are Samsung, SanDisk, Crucial and other brands.
Performance indicators of hard disks
The performance indicators of hard disks include:
Hard disk capacity: This is the most basic element of the hard disk, in megabytes (MB) or gigabytes (GB), indicating the total amount of data that the hard disk can store.
Rotational speed of the hard disk: Refers to the rotation speed of the motor spindle in the hard disk, the unit is rotational speed per minute (rpm), which affects the data transmission rate.
Interface type: Including IDE, SATA, SCSI, etc., affecting the speed and method of data transmission.
Cache size: The cache is a memory chip on the hard disk controller that has extremely fast access speed and acts as a buffer between the internal storage of the hard disk and the external interface.
Internal data transfer rate: Reflects the performance of the hard disk when the buffer is unused, depending on the hard disk's disk speed and disk line density.
External data transfer rate: Also known as burst data transfer rate or interface transfer rate, it is the rate of data transfer between the system bus and the hard disk buffer.
Average seek time: It refers to the time required for the magnetic head to move to the track where the data is located. It is an important indicator to measure the mechanical performance of a hard disk.
Single disk capacity: The amount of information that can be stored on a single platter affects the total capacity and integration of the hard disk.
IOPS: (Input/output operand per second). Indicates the random read/write performance of a hard disk.
Throughput: Unit: MB/s, reflecting the sequential read/write performance of disks.
Response time/delay: The interval between the time a request is made and the time a response is received, in ms or μs.
Continuous time without failure (MTBF): The maximum time from the start of a hard disk to the failure, expressed in hours (h).
Temperature of the hard disk surface: Indicates that the temperature generated by the hard disk increases the temperature of the hard disk enclosure.
These indicators together determine the performance of hard disks. Users should consider the importance of these indicators when selecting hard disks based on their own requirements.
Interface classification of a hard disk
From the overall point of view, the hard disk interface is divided into IDE, SATA, SCSI, Fibre Channel, M2-SATA, M2-Nvme and SAS seven, IDE interface hard disk is mostly used in household products, but also partly used in the server, SCSI interface hard disk is mainly used in the server market, and Fibre Channel is only in the high-end server. It's expensive. SATA is a new type of hard disk interface that is still in the market popularization stage and has broad prospects in the home market. Under the large category of IDE and SCSI, you can separate 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 specific hard disk interfaces, and their speeds differ greatly.
IDE
IDE's English full name is "Integrated Drive Electronics", that is, "electronic integrated drive", its original intention is to refer to the "hard drive controller" and "disk body" integrated together. The integration of the disk with the controller reduces the number and length of cables for the hard disk interface, increases the reliability of data transmission, and makes hard disk manufacturing easier because hard disk manufacturers no longer need to worry about whether their hard disk is compatible with controllers produced by other manufacturers. Hard disks are also easier for users to install. The IDE interface technology has been continuously developing since its birth, and its performance has been continuously improved, and its low price and strong compatibility have created a position that other types of hard disks can not be replaced.
IDE represents a type of hard disk, but in actual applications, people are also used to using IDE to call the earliest IDE type hard disk ATA-1, this type of interface has been eliminated with the development of interface technology, and then the development of more types of hard disk interface, For example, ATA, Ultra ATA, DMA, Ultra DMA and other interfaces belong to IDE hard drives.
The IDE hard drives have the following transmission modes: PIO(Programmed I/O) mode, Driect Memory Access (DMA) mode, and Ultra DMA(UDMA) mode.
The biggest disadvantage of the PIO(Programmed I/O) mode is that it consumes an extremely large amount of CPU resources. IDE interfaces running in PIO mode have data transfer rates ranging from 3.3MB/s(PIO mode 0) to 16.6MB/s(PIO Mode 4).
Direct Memory Access (DMA) mode is divided into Single-Word DMA and Multi-Word DMA. Single-Word DMA mode has a maximum transfer rate of 8.33MB/s, and Multi-Word DMA(Double Word) can reach 16.66MB/s.
The biggest difference between DMA mode and PIO mode is that DMA mode does not run with excessive dependence on CPU instructions, which can achieve the effect of saving processor operating resources. However, due to the emergence and rapid popularity of Ultra DMA modes, these two modes were immediately replaced by UDMA.
Ultra DMA Mode (UDMA) is a standard referenced under the Ultra ATA format, using the 16-bit Multi-Word DMA mode as a benchmark. One of the advantages of UDMA is that in addition to the advantages of DMA mode, it also uses Cyclic Redundancy Check (CRC) technology to enhance the performance of debugging and debugging during data transfer.
Since the introduction of the Ultra ATA standard, its interface has applied DDR(Double Data Rate) technology to double the transmission speed, and has been developed to Ultra ATA/100, its transmission speed of up to 100MB/s.
SCSI
SCSI English full name "Small Computer System Interface" (small computer system interface), is a completely different interface with IDE (ATA), IDE interface is the standard interface of ordinary PC, and SCSI is not specifically designed for the hard disk interface, It is a high-speed data transmission technology widely used in minicomputers. SCSI interface has a wide range of applications, multitasking, large bandwidth, low CPU usage, and hot swap and other advantages, but the high price makes it difficult to popularize as IDE hard disk, so SCSI hard disk is mainly used in medium and high-end servers and high-end workstations.
Fibre channel
The English spelling of the Fibre Channel is Fiber Channel, and the SCSI interface, the Fibre Channel is not originally designed for the hard disk interface technology, is specially designed for the network system, but with the storage system speed requirements, it is gradually applied to the hard disk system. Fibre Channel disk is developed to improve the speed and flexibility of multi-disk storage systems, and its appearance greatly improves the communication speed of multi-disk systems. Fibre Channel provides the following features: hot swappability, high-speed bandwidth, remote connection, and large number of connected devices.
Fibre Channel is designed for multi-disk system environments such as servers and can meet the high data transfer rate requirements of high-end workstations, servers, mass storage subnetworks, and peripherals for bidirectional, serial data communication through hubs, switches, and point-to-point connections.
SATA
The hard disk that uses the SATA (Serial ATA) port is also called the serial hard disk, which is the mainstream trend of the future PC hard disk. In 2001, the Serial ATA Committee composed of Intel, APT, Dell, IBM, Seagate, and Mactor formally established the Serial ATA 1.0 specification. In 2002, although the related equipment of Serial ATA was not officially listed, But the Serial ATA Committee has taken the lead in establishing the Serial ATA 2.0 specification. Serial ATA adopts serial connection mode, and serial ATA bus uses embedded clock signal, which has stronger error correction ability. Compared with the past, the biggest difference is that it can check transmitted instructions (not only data), and automatically correct if errors are found, which greatly improves the reliability of data transmission.
SAS
Serial Attached SCSI (SAS), Serial attached SCSI, is a new generation of SCSI technology, and the popular Serial ATA(SATA) hard disk is the same, are using serial technology to obtain higher transmission speed, and by shortening the connection line to improve the internal space. SAS is a new interface developed after the parallel SCSI interface. This interface is designed to improve the performance, availability, and scalability of the storage system and to provide compatibility with SATA hard drives.
SAS interface technology is backward compatible with SATA. Specifically, the compatibility of the two is mainly reflected in the compatibility of the physical layer and the protocol layer. At the physical layer, SAS interface and SATA interface are fully compatible, SATA hard disk can be directly used in the SAS environment, from the interface standard, SATA is a sub-standard of SAS, so SAS controller can directly control SATA hard disk, but SAS can not be directly used in the SATA environment. The SATA controller cannot control SAS disks. At the protocol layer, SAS consists of three types of protocols, which are used for data transmission according to different connected devices. The Serial SCSI protocol (SSP) is used to transmit SCSI commands. The SCSI Management Protocol (SMP) is used to maintain and manage connected devices. The SATA Channel protocol (STP) is used to transfer data between SAS and SATA. Therefore, with the cooperation of these three protocols, SAS can be seamlessly combined with SATA and some SCSI devices.
The Backplane of the SAS system can connect both dual-port, high-performance SAS drives and high-capacity, low-cost SATA drives. Therefore, SAS drives and SATA drives can coexist in the same storage system. However, it should be noted that SATA systems are not SAS compatible, so SAS drives cannot be connected to SATA backplanes. Because of the compatibility of the SAS system, users can use hard disks with different interfaces to meet the capacity or performance requirements of various applications, so that there is more flexibility in the expansion of the storage system, so that the storage device can maximize the investment benefit.
In the system, each SAS port can be connected to a maximum of 16256 external devices, and SAS takes direct point-to-point serial transmission mode, transmission rate of up to 3Gbps, it is estimated that there will be 6Gbps and even 12Gbps high-speed interface in the future. The interface of SAS has also been greatly improved, and it offers both 3.5-inch and 2.5-inch interfaces, so it can be adapted to the needs of different server environments. SAS relies on SAS extenders to connect more devices, and the extenders are mostly 12 ports, but according to the product development plan of the board manufacturer, there will be 28 and 36 port extenders introduced in the future to connect SAS devices, host devices or other SAS extenders.
Compared with the traditional parallel SCSI interface, SAS not only has a significant increase in interface speed (the mainstream Ultra 320 SCSI speed is 320MB/sec, while SAS has just started to reach 300MB/sec, and will reach 600MB/sec or more in the future), but also because of the use of serial cables, Not only can you achieve a longer connection distance, but also improve anti-interference ability, and this thin cable can also significantly improve the heat dissipation inside the chassis.
Size And Purpose of The Hard Disk Introduce
The size and purpose of the hard disk can be divided into:
0.85 inch, mostly used in mobile phones and other portable devices;
1 inch, mostly used in digital cameras (CF type II interface);
1.8-inch, for some laptops and external hard drive cases;
2.5-inch, commonly used in laptops and external hard drive boxes;
3.5-inch, most used in desktop computers. An external hard disk box with a 3.5" hard disk requires an external power supply.
5.25 inches, mostly used by early desktop computers. No manufacturer produces it today.
Hard disk interface comparison
SATA hard disk adopts the new design structure, data transmission is fast, space saving, and has many advantages over IDE hard disk:
1.SATA disks have higher transmission speed than IDE disks. SATA can provide a peak transfer rate of 150MB/s. In the future, it will reach 300 MB/s and 600 MB/s. We'll get transfer rates nearly 10 times faster than IDE hard drives.
2. Compared with the PATA40-pin data cable of the IDE hard disk, SATA cables are small and thin, and the transmission distance is long, which can be extended to 1 meter, making it easier to install the device and wire the machine. The small size of the connector, this cable effectively improves the air flow inside the computer, but also improves the heat dissipation in the chassis.
3. Compared with IDE hard disk system power consumption is reduced. A SATA hard drive runs on 500 milliamps of current.
4.SATA can be post-compatible with PATA devices by using a multi-purpose chipset or a serial-parallel converter. Since SATA and PATA can use the same drives, no operating system upgrades or other changes are required.
5.SATA jumper cables do not need to be set for the primary and secondary drives. The BIOS will number it in order of 1, 2, and 3. This depends on which SATA connector the drive is attached to (easy to install). The IDE hard drive needs to be set through the jumper to set the master and slave drives.
6.SATA also supports hot swappable and can be used like a USB flash drive. IDE hard drives are not hot-swappable.