Facts | Why data is not stored on a flash drive forever?




Our readers have shown a great interest in the topic of flash memory. In comments to the narrative on the life of flash drives have a question about the reasons which lead out with the passage of time is a data storage failure. As in most of the technical questions to him, there is a short answer. The complex reasons for flash drive becomes unfit for further use, deserves detailed consideration.

Which is flash memory?

About how to operate the flash drive, our readers already know . Nevertheless, there are some points to be covered in addition. The data on the flash drive can be erased and rewritten under the influence of electricity. These repositories of information in the course of its historical development became more comprehensive. But too much stick, wrapped in some cases not very high reliability. A large capacity, combined with decent reliability – too high a price. There are three main types of flash modules:

SLC (Single Layer Cell, single-layer cell). Can store in a single cell is only one bit of data. Is the most expensive type of flash drives, because less energy is consumed, has a higher recording speed and is used in industry as well as for storing important data.
MLC (Multi Layer Cell, multi-layer cell). Contains two bits in one cell. And consequently, is capable of storing twice as much information. MLC is most often used in consumer-grade products. In most cases, this memory is cheaper than SLC. It is characterized by a low endurance limit (compared to a single layer), and is able to withstand less rewrites.
TLC (Triple Layer Cell, three-layer cell). Contains one cell for three bits. TLC is the cheapest type of flash memory, while possessing a maximum density of information storage. Its endurance limit is significantly lower than the previously discussed types of flash memory. It is characterized by a rather low rate of reading and writing data. Usually used in cheap products. TLC is not recommended to store important data.

As is often the case, there are two sides of the issue. Those flash drives that can be stored in one cell of two or even three bits are cheaper. On this basis you can make larger drive capacities. But it affects the speed and reliability. The above information is also responsible to the question: Why stick a smaller amount often cost considerably more expensive than their much more intensive counterparts?

Flash drives have no moving parts, they work silently and quickly. Compared to other types of storage media, they are distinguished by their compactness. Flash memory is used in printers, lying on their boards, and being covered with plastic or a special rubber. Flash drives inserted into the USB-port of the computer or its reader with a special adapter. Modern computers do not need to put any special drivers to support flash drives. Do not need them, and an additional power supply.
Causes of damage and the gradual degradation of a flash drive

О флешках

Most of the damage to the flash drive are the same factors that cause the battery to lose its charge after a few hundred charge cycles. Thousands of write cycles lead to the fact that the modules NAND-flash lose their ability to retain data. SLC-flash ten times more resistant in this regard than MLC-flush and twenty times than the TLC-flush. For this reason, for industrial applications use the most reliable type: SLC, and consumer devices “mediocre» MLC.

The older USB flash drive, so it is less reliable. This process is called progressive degradation. This occurs as we age, even in those cases where the flash drive has not been explicitly expressed by the adverse effects of the environment and has not been physically damaged.

Factor affecting the reliability and durability of the stick is called [the ability to] retain [the information]. In English simply “retention» («retention»). “Hold” describes how long the memory cell is able to maintain its previously programmed state. This factor is very sensitive to the environment. High temperatures lead to a reduction of “hold”. The number of write cycles also leads to retention, especially useful when it is working with the TLC-drives.

Under high temperature and high humidity condensation which leads to corrosion of contacts and adversely affects the chip.

But the most common cause of data loss on a flash drive is its improper shutdown of the computer or other device. The consequence of improper shutdown may result in damage to the file system. Normally in this situation, even if the data is lost, the drive itself is physically intact.

But in some rare cases, improper shutdown stick can lead to damage to the cells of flash memory in which information is stored inside the flash drive. In such cases, it becomes impossible to drive to access the operating system, and hence it is impossible to restore its performance, and using the appropriate software tools. To retrieve information in such a situation, you will need professional help. To avoid such damage, always disconnect the USB flash drive correctly. Especially dangerous is to stick it off in the process of reading or writing data.

Since the flash drive in any case are adversely affected, it is somehow subject to gradual degradation. Ideal conditions in the real world just does not happen. In more favorable conditions (in the absence of other injuries and the impact of other factors) flash drive will last longer, too, but not forever. Over the years, become yellow and brittle paper, rust and sometimes crumbles into dust iron. Flash card is no exception to the general rule covering all subjects who are exposed to whatever influences.
How to avoid the loss of data memory stick?

О флешках

Since degradation is inevitable, it is necessary to take precautions. It is quite common to back up important data. Appliances, alas, is not perfect. Data recovery experts in some cases, are able to “pull” information from the damaged vehicle, but it is expensive and takes time. Yes, and confidence that the data will be saved and there can not be. So backup is preferred.

Given the limitations of Flash technology, the data on these drives do not update too often. For critical data and applications is better to use a more reliable flash memory, a single-layer SLC.

The USB flash drive should be recovered by the rules and never disable it in the process of reading and writing data. Necessary to avoid exposure to the flash drive high temperatures, high humidity, and pressure.

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