The classes of memory cards did not appear immediately, the first SDs did not have this accessory, but with the increase in the number of models produced by different manufacturers, the need to somehow separate the products became obvious. To this end, a consortium of the above format invited all companies issuing SD cards to use gradations developed by the organization. So, from the moment the standard for SD cards became universal, all devices were divided into four groups: class 2, 4, 6 and 10. The number means the minimum speed in megabytes at which recording to this card will occur. Thus, if you have a class 10 device in your hands, this means that it is capable of receiving a data stream of 10 Mb / s, but if it is labeled "class 4", it means that it can write at a speed of 4 Mb / s.
Why was the recording speed chosen as the main parameter? Everything is very simple, digital devices working in HD or having a small memory buffer should be able to reset everything recorded on the card, and here it is just that the slow write speed can become a bottleneck. So if you need a microSD card for a camera or camera, you should carefully look at the requirements of the gadget for the required class. The wrong choice can cost you not only wasted money for the drive itself, but also a spoiled video recording of some important moment in life.
Let's take a closer look at the classes of memory cards.
The second, as mentioned above, is capable of a maximum speed of 2 Mb / s, only cheap and very slow devices belong to it. This type of card is used in MP3 players, video players, printers and various photo frames. In a word - in those devices for which recording speed is not so important. But the use of this class in camcorders and digital cameras is not recommended.
The fourth class with a write speed of 4 Mb / s is perfect for most "home" applications. Non-professional cameras and SLR cameras will work quite normally with such a card. If you do not need to record a 1080p stream, then its performance will suffice with your head.
If the first two groups are suitable only for non-professionals, then the sixth and tenth classes of memory cards are suitable for more advanced models of digital video technology. Specifically, the sixth group with a recording speed of 6 Mb / s will give you the opportunity to save RAW quality photos and take a series of pictures.
Well, professionals, whose requirements for speed are well known, use only the tenth, fastest class. And it’s not surprising, because the matrices of modern SLR cameras are capable of generating gigantic amounts of information, and these voracious monsters require fast recording devices. Previous classes of memory cards simply can not cope with these volumes, so the natural choice is the tenth class. But the price of such products fluctuates around 1000 rubles per unit of 32 GB.
Let's move on from hardware issues to software ones. In the second part of this article, I would like to talk about such a program for checking memory cards and flash drives as H2testw. This product is designed to diagnose portable storage devices for failures, inaccuracies or corrupt clusters.
If you are the “happy” owner of a bad SD card, H2testw will quickly determine the nature of the malfunction and how many memory cells have been damaged. Having received such information, you will have to decide what to do, whether to throw the device away or work with it further.
To run the program, you need to perform an extremely simple set of actions by inserting your media into the USB or SD connector, click on “Select”, choose what to check and how. If you need to conduct a full analysis, then you need to click the "Write and Verify" button. At the end of the verification process, H2testw reports what problems it detected, what speeds the scanned device supports, and a lot of other useful information.