|Ⅰ External hard drive characteristics|
|Ⅱ How to use the external hard drive?|
|Ⅲ How to select an external hard drive?|
|Ⅳ Technical Parameters|
The external hard drive is mainly composed of the shell, the circuit board (including the control chip and the data and power interface), and the hard drive. The shell is generally made of aluminum alloy or plastic material, which has the functions of compression resistance, anti-vibration, anti-static, anti-fall, moisture-proof, and heat dissipation; the control chip controls the read/write performance of the external hard drive; the common data interfaces are USB and IEEE1394.
External Hard Drive
External hard drives can provide considerable storage capacity and are a more cost-effective mobile storage product. External hard drives can provide users with larger storage capacity and good portability within a price range that users can accept. The external hard drives currently on the market can provide 320GB, 500GB, 600G, 640GB, 900GB, 1000GB (1TB), 1.5TB, 2TB, 2.5TB, 3TB, 3.5TB, 4TB and other capacities, up to 12TB capacity, to a certain extent meet the needs of users. With the development of technology, the capacity of external hard drives will become larger and larger, and the volume will become smaller and smaller.
Most external hard drives use USB, IEEE1394, and eSATA interfaces, which can provide higher data transfer rates. However, the data transfer rate of the external hard drive is limited to a certain extent by the interface speed, especially on products with the USB1.1 interface specification. When transferring larger data, it will test the patience of users. The USB2.0, IEEE1394, and eSATA interfaces are much better. The transfer rate of the USB2.0 interface is 60MB/s, and the transfer rate of the IEEE 1394 interface is 50-100MB/s. When exchanging data with the host, it only takes a few minutes to read a large file on the order of gigabytes, which is especially suitable for storage and exchange with video and audio data.
Nowadays, PCs are basically equipped with USB functions. The motherboard can usually provide 2~8 USB ports, and some displays also provide USB adapters. The USB interface has become a necessary interface in personal computers. USB devices do not need to install drivers in most versions of WINDOWS operating systems, and have a true "plug and play" feature, which is flexible and convenient to use.
Data security has always been the most concerned issue of mobile storage users, and it is also an important criterion for people to measure the performance of such products. The advantage of the external hard drive lies in the safety and reliability of its stored data. This type of hard drive has a similar structure to that of a laptop hard drive, and most of them use silicon-oxygen disks. This is a disc material that is stronger and more durable than aluminum and magnetic and has a larger storage capacity and better reliability, which improves the integrity of the data. The use of silicon-oxygen disk drives is characterized by a smoother disk surface, which effectively reduces the number of irregular disk surfaces that may affect data reliability and integrity. Higher disk surface hardness makes USB hard drives highly reliable.
1 First, insert the external hard drive into the USB port of the computer.
2 Then click the USB flash drive icon on the desktop of the computer.
3 Then you can copy the data in the hard drive or copy the data in the computer into the external hard drive.
4 Then click the USB flash drive icon at the bottom left of the screen.
5 Finally, click on the safe pop-up, and the external hard drive can be pulled out normally.
Pay attention to the problems in the use of external hard drive:
(1) The connection of the external hard drive: The USB connection line of the external hard drive is both a data transmission line and a hard drive working power supply line. If the connection is too long, it will cause increased resistance and data interference, which will make the external hard drive unable to work normally. The USB adapter cable should be as short as possible. Except for the original configuration cable, it is not suitable to connect the extension cable; second, the USB interface on the back of the chassis (the interface directly fixed on the motherboard) should be used to connect to the computer, rather than the interface on the front of the chassis. (They are connected to the front panel by a lead from the motherboard).
External Hard Drive
(2) External power supply of the external hard drive: When the external hard drive is working, the power supply of the hard drive and the data interface is provided by the USB interface of the computer. However, when using an external hard drive of 10GB or more, relying solely on the USB cable to supply power to the hard drive may not work properly due to insufficient power. At this time, an external auxiliary power supply (DC stabilized power supply) must be used.
(3) Although the external hard drive adopts the USB interface, it can support hot-plugging, but it should be noted that in the use process, you’d better close the USB interface before you unplug the USB connection (click the USB interface mark next to the date).
1.External hard drive shell: The material of the external hard drive shell is generally divided into two types: metal and plastic. Generally speaking, the compression resistance and heat dissipation performance of the metal casing will be better, while the plastic casing has relatively more advantages in terms of shock resistance and weight.
2.PCB board control chip: The control chip on the external hard drive PCB is directly related to the reading and write performance and stability of the product. At present, the control chip is mainly divided into two grades: high and low. The characteristics of high-end control chips: the price is more expensive, the stability and compatibility are very good, and it is the first choice for high-end users. The characteristics of low-end control chips are: the stability and data transmission performance are relatively poor, but they are enough to meet the daily work needs. Because of their low price, they are mostly used in low-end hard drive boxes.
3.External interface of hard drive box: The mainstream interface of the external hard drive is high-speed USB2.0 and LiSB3.0. IEEE1394 or eSATA interface can be seen on high-end products. IEEE1394 interface is divided into two types: IEEE1394a and IEEE1394b: IEEE1394a interface data transfer rate theoretically can reach 400Mbit/s (50MB/s); the transmission rate of the IEEE1394h interface can reach 800Mbit/s (100MB/s). In theory, SATA can reach 3Cbit/s, which is the development direction of external hard drives in the future.
4.Quality: There are many so-called branded external hard drives on the market that are actually assembled by distributors. In other words, manufacturers provide distributors only with external hard drive boxes. After the dealers get the boxes, they can install the hard drives in them. The quality of various brands of external hard drives cannot be guaranteed. Parallel-imported hard drives or even repaired hard drives are likely to be put into external hard drive boxes by profiteers and sold to unsuspecting consumers. When purchasing this type of product, please recognize the product's trademark and anti-counterfeiting mark, and ask the dealer for the official invoice and three packs of cards.
Speed is an important indicator to measure the performance of the external hard drive, which mainly depends on the data transfer rate and rotation speed of the hard drive.
Internal of External Hard Drive
(1) Data transfer rate
The data transfer rate of the hard drive emphasizes the internal transfer rate (the data transfer rate between the hard drive head and the cache), while the external hard drive refers more to the data transfer rate of its interface. Because the external hard drive is connected to the system through an external interface, the speed of its interface limits the data transfer rate of the external hard drive. Although the current USB1.1 interface can provide 12 Mbps; USB 2.0 interface can provide 480 Mbps; IEEE 1394a interface can provide 400 Mbp; IEEE 1394b can provide 800 Mbps data transfer rate, in actual applications, the transmission rate in the application will be slowed down due to some reason.
(2) Rotating speed
The speed of ordinary hard drives for household use is generally 5400pm, 7200 rpm, etc. High-speed hard drives are now the first choice for desktop users; for notebook users, they are mainly 4200 rpm and 5400 rpm. Although some companies have released 7200rpm notebook hard drives, it is still relatively rare in the market.
The reading speed of mainstream 2.5-inch brand external hard drives is about 15-25MB/s, and the writing speed is about 8-15MB/s. If you copy a 4GB DVD movie to an external hard drive at a write speed of 10MB/s, it will take about 6 minutes and 40 seconds. If you copy a 4GB DVD from the external hard drive at a read speed of 20MB/s, it takes about 3 minutes and 20 seconds to transfer the movie to the hard drive of the host computer.
For a notebook computer, when the 2.5-inch USB external hard drive is working, the hard drive and the data interface are powered by the USB interface. The USB interface can provide a 0.5A current, and the working current of the notebook computer hard drive is 0.7~1A, and there will be no problems in general data copying. However, if the capacity of the hard drive is large or the file to be moved is large, it is easy to have an insufficient power supply, and if the USB interface supplies power to multiple USB devices at the same time, it is also easy to have the insufficient power supply, causing data loss or even hard drive damage. In order to strengthen the power supply, 2.5-inch USB external hard drives generally provide a power cord that takes power from the PS/2 interface or the USB interface. The removable hard drive needs to be connected to the PS/2 power cord when moving large files.
At present, external hard drives can be divided into three types according to their size: 3.5-inch desktop hard drives; 2.5-inch notebook hard drives; 1.8-inch mini hard drives. Among them, the 3.5-inch desktop hard drive has the advantages of fast speed and large capacity, but it is large in size, heaviest and inconvenient to carry. And because the hard drive is designed for desktop computers, it has poor shock resistance, but it still has the advantages of price and capacity. 2.5-inch notebook hard drives are specially designed for notebooks. They are small in size and weight. They are also specially designed for shock resistance. They have good shock resistance and are currently the most widely used in external hard drives. The 1.8-inch mini hard drive is also designed for notebooks. It has good shock resistance, and its size and weight are the smallest of the three. However, its price is higher, and its capacity is smaller. It is difficult to popularize, and it is more suitable for users with special needs.
Capacity is the storage space of the external hard drive. At present, 250G and 320G products are quite cost-effective. The 320G product market is quite mature and the price is very reasonable. And 400G or above products are still high-priced series, and ordinary users rarely consider it. Although 160G and 250G are mainstream capacities, they are limited by cost and actual usage requirements. For general office and home applications, choosing 80G or even lower 40G can fully meet the needs.
In terms of shock resistance, the spindles of 2.5-inch notebook hard drives use FBD (FluidDynamicBearing) fluid-bearing motors. The oil film is used to replace the balls, which effectively avoids the high temperature and noise caused by the friction of the balls. On the other hand, notebook hard drives generally use "zero-touch" head start-stop technology. In the non-working state, the head is in the docking area and does not touch the disc. When working, the flying height of the magnetic head is low, the surface of the advanced silicon-oxygen disc is smooth, and the probability of scratches caused by accidental vibration of the magnetic head during operation is also greatly reduced. These technologies have reduced the probability of damage to the external hard drive during the movement. Therefore, many original well-known brand hard drives have passed hundreds of drop tests from different angles in professional laboratories.