How to choose a proper memory card?

Friends familiar with the storage industry will notice that the prices of all kinds of storage products have returned to normal state recently. On the one hand, the mainstream 8GB DDR4 memory has been reduced from nearly $149.25 to about $44.78 and the prices of solid-state drives of all brands have basically maintained at $0.15-$0.22 per GB. On the other hand, the price of SD, CF and other memory cards has also dropped a lot. Although the demand for memory cards has decreased a lot in recent years, some special devices, such as digital cameras, Switch hosts, smart routers and so on, still need to be equipped with high-quality memory cards. Therefore, we will talk about how to choose memory cards in this paper.
Question: What kinds of memory cards are divided into?
Answer: The types of memory cards are greatly various, including CF cards, MMC cards, SD cards, memory sticks and so on. Among them, SD cards are upgraded versions of MMC cards. Each memory card is divided into different subtypes. At present, The most widely used memory cards in our daily life are SD cards and their similar products TF card. In addition, Some special cameras will use CF cards.

 
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Question: What are the brands of memory cards and what is the overall price at the moment?
Answer: The main brands of memory cards include Samsung, SanDisk, Kingston, Toshiba, Sony, Lexar and so on. The price depends on reading and writing speed, capacity and stability of memory card. General products cost at about $0.15 per GB, while high-end memory cards can even reach $1.5 per GB.

 

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Question: What do the various parameters and identifications in the memory card mean?
Answer: At present, there are several mainstream memory card identifications. First of all, speed identifications include two kinds, Class and UHS. Class level can be divided into Class 0, 2, 4, 6, 10 and so on according to the different speed. The number of Class represents the minimum writing speed of this product in MB/s. For example, Class 10 represents the minimum writing speed of this memory card over 10MB/s.

 

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UHS represents the bus standard of memory card, and introduces two parameters of reading and writing speed. UHS-I means reading speed of memory cards up to 50MB/s and writing speed up to 104MB/s. In addition, parameters of UHS-II and UHS-III are higher, but the price is also rising. For example, in terms of TF card with capacity of 256GB, UHS-I standard products need less than $44.78, while UHS-II products cost at $373.13.

 
Image from Wikipedia
Another identification is for random read performance of memory card. Random read and write performance of A1 specification product is 1500 IOPS/500IOPS, while that of A2 specification product is improved several times.
Question: Why do different brands of memory cards perform variously?
Answer: There are many factors that affect the speed of memory cards. Because of different positioning, speed performance will vary greatly in different brands, even in the same brands.. For example, some special memory cards for traffic recorders and monitoring equipment focus on service life rather than reading and writing speed. Even though some products are dedicated for random reading and writing speed, its speed is not high in normal state.
In short, the main factor affecting speed in the products of several front-line manufacturers is product series and positioning, while brands lead to very little difference. However, some products performance is affected by some small manufacturers due to quality control and technology. Therefore, it is recommended that friends who are ready to buy memory cards choose famous brand products. They should not be greedy for cheaper products, for subsequent quality problems may lead to data loss, resulting in irreparable consequences.