As the name implies, mobile hard disk is a storage product that takes hard disk as storage medium and emphasizes portability. At present, the vast majority of mobile hard disks on the market are based on standard hard disks, and only a few are micro hard disks (1.8 inch hard disks, etc. ), but the price factor determines whether the mainstream mobile hard disk is based on the standard notebook hard disk. Because the hard disk is used as the storage medium, the data reading and writing method of the mobile hard disk is the same as that of the standard IDE hard disk. Mobile hard disks mostly use faster transmission interfaces such as USB, IEEE 1394, which can transmit data with the system at a higher speed.
1。 interface type
Interface type refers to the interface type used by the mobile hard disk to connect to the computer system, not the interface type of its built-in hard disk. Because the mobile hard disk can only be connected to the system through the interface, the interface determines its connection performance and data transmission speed with the system. When choosing a mobile hard disk, the first thing to consider is its interface type. At present, USB and IEEE 1394 interfaces are mostly used in mobile hard disks, among which USB 1. 1 interface can provide12 Mbps; USB 2.0 interface can provide 480Mbps；; IEEE 1394a interface can provide 400Mbps；; IEEE 1394b can provide data transmission rate of 800 Mbps. However, these are the maximum data transmission rates that the interface can achieve in an ideal state. In practical application, due to some objective reasons (such as the main control chip used in storage equipment, the quality of circuit board, etc.), the transmission rate will slow down. ).
Universal serial bus
Mobile hard disk box of USB interface is the mainstream interface, which supports hot plug. There are two USB standards, USB 1. And the transmission speed of USB 2.0. USB 2.0 is as high as 480Mbps, which is 40 times that of USB 1. 1 interface. USB2.0 needs the support of the motherboard, but it is backward compatible. Mobile hard disk box of the same brand USB2.0 is 30 ~ 50 yuan more expensive than USB 1. 1. However, considering the huge speed difference and the fact that USB2.0 has become the mainstream of the market, it is recommended to buy a mobile hard disk box that supports USB2.0. Even if your current motherboard does not support it, you can prepare for future upgrades.
IEEE 1394
IEEE 1394, also known as FireWire, was put forward by Apple in the mid-1980s and is the standard interface of Apple computers. Its data transmission speed can theoretically reach 400Mbps, which supports hot dialing. However, only some high-end PC motherboards are equipped with IEEE 1394 interface, so its popularity is poor. Recommended to friends with special needs.
At present, there are many mobile hard disk box with USB 2.0+IEEE 1394 dual interfaces in the market, which are more flexible in configuration, but the price is relatively high.
Second, the storage medium, data transmission rate and speed
storage medium
Storage media refers to the type of hard disk media used inside the mobile hard disk. At present, there are three kinds of hard disks used in mobile hard disks: 3.5-inch desktop hard disks; 2.5-inch notebook hard disk; 1.8 inch micro hard disk. Among them, the 3.5-inch desktop hard disk is the most widely used hard disk product in DIY market, which is specially used for desktop systems and is the largest and heaviest of the three hard disks. And because it is used on the desktop, there is no special design for shock prevention. This kind of product is used in mobile hard disk, which reduces the security of data to a certain extent and is inconvenient to carry, but it still has certain advantages in price and capacity. The 2.5-inch notebook hard disk is specially designed for notebooks, and it also has a special design in shock prevention. It has good seismic performance, small size and light weight, and is widely used in mobile hard disks at present. 1.8 inch micro hard disk is also designed for notebooks, which is not a problem in earthquake resistance, and its volume and weight are the smallest among the three, but its price is still at a high level, so it is still difficult to popularize, and it is more suitable for users with special needs and its capacity is relatively small.
rate of data signalling
Different from hard disk products, the data transmission rate of hard disk emphasizes the internal transmission rate (data transmission rate between hard disk head and cache), while the data transmission rate of mobile hard disk is more about its interface. Because the mobile hard disk is connected to the system through an external interface, the speed of its interface limits the data transmission rate of the mobile hard disk. Although the current USB 1. 1 interface can provide12 Mbps; USB 2.0 interface can provide 480Mbps；; IEEE 1394a interface can provide 400Mbps；; IEEE 1394b can provide data transmission rate of 800 Mbps, but in practical application, due to some objective reasons (such as the main control chip used in storage devices, the quality of circuit boards, etc.), the transmission rate will slow down. For example, a mobile hard disk product with USB 1. 1 interface, one can provide the reading speed of 1.2MB/S, and the other can provide the reading speed of 900KB/S, which is caused by the difference between the main control chip and other components.
Lift front wheel speed
Ordinary household hard disks usually rotate at 5400 rpm and 7200 rpm, and high-speed hard disks are also the first choice for desktop users. For notebook users, it is mainly 4200 rpm and 5400 rpm. Although some companies have released 7200rpm notebook hard disks, they are still rare in the market. Server users have the highest requirements for hard disk performance. The rotational speed of SCSI hard disks used in servers is basically 10000 rpm, and even 15000 rpm, which is much better than household products.
Three, the size of the mobile hard disk (box)
Mobile hard disk box is divided into 2.5 inches and 3.5 inches. The 2.5-inch mobile hard disk box uses a laptop hard disk, and the 2.5-inch mobile hard disk box is compact and portable, and generally has no external power supply.
The 3.5-inch hard disk box uses a desktop computer hard disk, which is huge and relatively poor in portability. A 3.5-inch hard disk box usually comes with an external power supply and a cooling fan.
Fourth, the power supply problem.
When the 2.5-inch USB mobile hard disk works, the hard disk and data interface are powered by the computer USB interface. USB interface can provide 0.5A current, while the working current of notebook computer hard disk is 0.7 ~ 1A, so general data copying will not be a problem. However, if the hard disk capacity is large or the mobile files are large, it is easy to have insufficient power supply, and if the USB interface supplies power to multiple USB devices at the same time, it is easy to have insufficient power supply, resulting in data loss or even hard disk damage. In order to strengthen the power supply, 2.5-inch usb hard disk box generally provides power cord and obtains power from PS/2 interface or USB interface. Therefore, when moving large files, you need to connect the PS/2 power cord.
3.5-inch hard disk boxes generally have their own external power supply, and the power supply is basically no problem. The IEEE 1394 interface can provide the maximum current of 1.5A, so there is no need for an external power supply.
Verb (abbreviation of verb) major brands and market division
The mobile hard disk box market is clearly divided into different grades of products, with prices ranging from less than 40 yuan to more than 200 yuan. The cost of mobile hard disk box is mainly on the chip. At present, ISD300 chip of In-System company and ALi M5621chip of Ali company are generally used for high-end products in mobile hard disk box with USB2.0 interface, while GL8 1 1 chip of Genesys Logic company is mainly used for some low-cost products. High-end products have stable performance and good compatibility, and some products also have very practical functions such as USB HUB. Mobile hard disk box brands with good quality in the market include Newman, Mobile Star, Patriot, Bestler and Tsinghua Tongfang.
I fully recommend Panther 2.0 series from Tsinghua Tongfang, which I personally think is the most cost-effective brand mobile hard disk.
Tsinghua Tongfang UD2240(40G) Quotation: 970 yuan.
Design hard disk
Storage capacity 40GB
USB2.0 interface type
The design of aluminum-magnesium alloy shell is exquisite and durable.
Overall dimensions117× 72×11mm.
Other 2.5-inch hard disks support plug and play and are compatible with ATA/atapi-6; Anti-magnetic and shockproof, data can be stored for a long time.
Tsinghua Tongfang UD2240(60G) Quote: 1380 yuan.
Design hard disk
60GB storage capacity
USB2.0 interface type
The design of aluminum-magnesium alloy shell is exquisite and durable.
Overall dimensions117× 72×11mm.
Other 2.5-inch hard disks support plug and play and are compatible with ATA/atapi-6; Anti-magnetic and shockproof, data can be stored for a long time.
Seven, PS, pay attention to the problem:
1, many of the above contents are based on reprinting, because I think the technical terms are more authoritative. After all, the brand is a 1000-yuan gadget, which is not convenient for testing.
2. Generally speaking, I noticed that the mobile hard disk discussed on dolc is mainly 3.5 inches. Personally, I think that 3.5 inches can't reflect the word "mobile" of mobile hard disk, so it is better to back up files and movies. Moreover, the 3.5-inch hard disk should be dIY-based, and attention should be paid to the shockproof, heat dissipation and power supply of the hard disk box itself when purchasing. It is more cost-effective to use maxtor and Seagate's hard disks. If you buy ready-made, try to buy brand, because the price is not high.
3. About the 2.5-inch hard disk I recommended, the reason is that I have been using Tsinghua Tongfang, and I feel good, and the cost performance is quite high. Here, I want to remind you of two points: 1. Some models of Patriot's mobile hard disks are very expensive, not because they have many functions or outstanding shock-proof performance, but because they are truly technical mobile hard disks, that is to say, their disks are hard disks such as nickel disks. Tsinghua Tongfang put a separate hard disk in it. I bought the mobile hard disk last year, and it has been used for more than one year. I feel that the interface between usb and mobile hard disk is sometimes in poor contact. But my classmate just bought a new Tsinghua Tongfang mobile hard disk today, and I think its interface has been improved, so it should not be a problem. Recommend it. Of course, in this respect, I think the best is trekstor of Germany.
4. In terms of power supply, generally speaking, a usb interface is enough for power supply. However, it is possible that you need to connect two interfaces at the same time, but I found that the recent Centrino notebook canceled the ps/2 interface, so you must pay attention to what the two interfaces it provides you to avoid investment failure.
5. Shockproof, moistureproof and antimagnetic are the main problems to be paid attention to when using, but I don't think these are problems if you don't exaggerate. Just take care of it normally.