SD card Class Meanings
Every other day the SD association brings in innovations to the SD technology because of its extensive use and to come up to the needs of the consumers. All types of SD cards with varying size and storage capacity come with different speeds. These speeds allow great versatility for the consumers as they have options to select from and can choose the most appropriate one for their device.
Earlier on, there was no specific standard for SD card classes and therefore companies indicated the transfer rates in their own manner. It was impossible to know whether the speed the cards indicated would be the actual speeds when used in the device. This caused issues about the reliability and performance and caused problems for the consumers. The SD card association then came up with a standard SD speed class. This enabled consumers to be able to do easy comparison of different cards available.
Each SD card specifies the speed class for the card which is the minimum data transfer speed. There are three classes which includes class 2, class 4 and class 6. The class 2 transfers the data at a minimum rate of 2MB/s. Class 4 transfers the data with the minimum speed of 4 MB/s and class 6 comes with the minimum transfer speed of 6 MB/s. This allows you to choose the card with the speed that is most compatible to the device.
With the higher the speed of the SD card, there will be less fragmentation and therefore, with the increasing data, there are lesser chance of speed reduction. Each SD card now gives the operating conditions which are the conditions in which the SD card will work best. So if one wants to have the same speed for the SD card while in use, these conditions must be considered.
SD cards with new speed classes are divided into small memory units. This is known as fragmentation. The data is written on units where no previous data is stored. The host device identifies such units and writes on those that meet the speed requirement of the card it is using. As the amount of data stored is increased there is more fragmentation which reduces the write speed. Therefore, there is a minimum and maximum speed with which SD cards work.
One thing that must be kept in mind is that the read and the write speed can vary according to the conditions. These conditions specifically include the device you use and the file size you are intending to read or write. Therefore, before one buys any SD card, it is very important that the speed class compatibility with the device is taken into consideration.