The storage medium is the first thing to solve for data storage, the carrier of data storage, and the foundation of data storage.Storage media is not the more expensive the better, the more advanced the better. It is necessary to select storage media reasonably according to different application environments.Common data storage media are:mobile hard disk drive, recordable CD, MP3, MP4, U disk, flash memory card, etc.
Chinese name
Data storage media
Foreign name
Data storage medium
Definition
Data carrying objects
Common types
U disk, removable hard disk, flash memory card, etc
The storage medium isdata storage The first problem to be solved is the carrier and foundation of data storage.Storage media is not the more expensive the better, the more advanced the better. It is necessary to select storage media reasonably according to different application environments.[1]
The data storage of multimedia requires large capacity, fast storage speed, convenient carrying and universal interface with computers.In addition to the large capacity hard disk of the computer to store multimedia data, the data storage media meeting the above requirements are:mobile hard disk drive, recordable CD, MP3, MP4, U disk, flash memory card, etc.[2]
Common types
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removable hard disk
Mobile hard disk is also called active hard disk orUSBHard disk (different from the traditional hard disk connected through the movable hard disk rack), the mobile hard disk isHard diskIt is a storage medium that emphasizes portability.Most of the mobile hard disks in the market are based on small hard disks (2.5 inches in diameter) of notebook computers, while only a few are based onMicro hard disk(1.8 inch hard disk, etc.).Since the hard disk is used as the storage medium, the data read/write mode of the mobile hard disk is the same as that of the standard IDE hard disk.The mobile hard disk adopts USB 2.0, USB 3.0, IEEE 1394 and other interfaces with fast transmission speed, which can transfer data with the computer at a high speed.The storage capacity ranges from several hundred gigabytes to several terabytes.[2]
Since the first standard (USB 1.0) was published in February 1996, USB (Universal Serial Bus) standard has been applied in three aspects: USB 1.0 (transmission rate: 1.5Mbit/s), USB 1.1 (transmission rate: 12Mbit/s), USB 2.0 (transmission rate: 480Mbit/s) and USB 3.0 (transmission rate: 5.0GMbit/s).USB interfaceWith its own power supply, it can provide power for low power consumption equipment.So common devices with USB interface, such as MP3 playersmobile hard disk drive, digital camera, etc. do not need additional power supply. When connected to the computer systemAutomatic drive。[2]
Solid state hard disk
Solid state hard disk, or SSD for short, is a hard disk made of solid state electronic memory chip array.There are two kinds of storage media for SSDs, one is to useFlash Memory(Flash chip) as the storage medium, and the other is to useDRAMAs a storage medium.The former is like a high-speed, high-capacity USB flash disk, which can be used for mobile storage, while the latter is mainly fixed in the computer for high-speed data storage. It is a high-performance memory, and has a long service life. The drawback is that an independent power supply is needed to protect data security.DRAM solid state disk is a non mainstream device. Desktop computers and laptops often use SSDs for the first storage disk, where the operating system is installed, so that the boot is fast and reliable.[2]
Recordable disc
The commonly used recordable discs are divided into CD-R, CD-RW, DVD ± R/RW formats.
（1）CD-RIt is a disc that can be burned once and read for many times. The standard capacity is 650MB, but the common one can burn 720MB.CD-R supports multiple non repetitive recording until the capacity is full, but it takes 20MB of index space each time.CD-R recording speed is 52 × high.
（2）CD-RWIt is a disc that can be burned and rewritten repeatedly, with a capacity of 650MB.There are CD-R mode and FILE mode for writing information. The former has good compatibility with the recorded information, while the latter can only be used on the recorded machine. However, writing information is as convenient as using a disk (using FILE recording software) for writing and deleting.
（3）DVD。There are two mainstream DVD recording discs: DVD-R/RW and DVD+R/RW.The former is the DVD recording format of the main booth of companies such as Pioneer, which mainly supports DVD video recording.The latter is the recording standard promoted by Sony, Philips and HP, which mainly supports data recording.There are DVD-5, DVD-9, DVD-10, and DVD-18 read-only DVD discs (active discs) in use.[2]
Magneto-optical disk
Magnet Optical (MO) and other storage media, whose size is only 3.5in, are easy to carry and can be read at any timeDiscInformation on.The most common types on the market are 230MB and 640MB. Recently, a 1.3GB MO has been launched, and the cost of MO per MB is about 0.25 yuan.Most of them are used in the so-called impact output center, or where the computer art editors store data.[3]
USB drive
The USB flash disk is a flash storage device.It utilizes FlashNAND Flash (Flash RAM, electrically erasable memory)mobile storage。USB (Universal Serial Bus) interface is adopted, and the rewritable performance greatly enhances the security of data.It is extremely convenient to use, without external power supply, and supports plug and play and hot plug, as long as there isUSB interface, you can use the USB stick.MP3 and MP4 players developed from U disks can also be used as data storage devices.[2]
Flash card
It is generally used in digital products, such as mobile phones, digital camerasDigital video camera、Digital recorderEtc.Common types are: SD card, miniSD card, microSD (TF) cardCF card、Memory stickEtc.The most used TF card, TransFlash, also known as Micro SD card, was jointly developed by Motorola and Sandisk and launched in 2004. According to the write rate, it can be divided into ordinary type and HC type (high-speed type), some of which are classified by Class2~10, with the write rate of 2~10MB/s.Class0 is not marked, and Class2 can meet the requirements of watching ordinary MPEG2 and MPEG4 movies and digital camera shooting;Class4 can smoothly broadcast the continuous shooting requirements of high-definition television (HDTV) and digital camera;Class6 or above meets the needs of SLR camera for continuous shooting and professional equipment.Generally, ②~⑩ is used on the TF card to indicate Class2~Class10.[2]
General selection principles
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Although the value of data is different, its life cycle stage is different, and the requirements for storage media are different, the following issues must be considered in any case:
Medium durability
The storage medium with high durability is not easy to be damaged, reducing the risk of data loss.Therefore, media with low environmental requirements, no damage and high durability shall be selected for data storage.[4]
Proper capacity
The high capacity of media is not only conducive to the reduction of storage space, but also easy to manage, but will increase the cost of storage.For large capacity data, if the storage medium capacity is low, it will not be conducive to the integrity of the storage data.It is better to match the storage capacity of the media with the amount of data managed.[4]
Low cost
The low price of media can reduce the cost of storage management and system operation.[4]
Wide acceptability
In order to reduce the risk that the IT industry does not support storage media, storage media with wide availability should be selected, especially those that meet industrial standards.[4]
