2024-04-24

Flash Device

Data recovery apparatus and method used for flash memory

DATARECOVERYUNION.COM08 mins

Flash data recovery1. A data recovery apparatus used for a flash memory that includes data areas and index areas in which values indicating whether data stored in the respective data areas are valid are recorded, comprising: a controller that performs a data operation at each of a plurality of logical addresses, and if the data operations performed at the plurality of logical addresses are successful, records a mark value in a last index area of a plurality of index areas respectively corresponding to the plurality of logical addresses.

2. The data recovery apparatus of claim 1, wherein the data operation is first performed on a middle portion of the flash memory and then on other portions of the flash memory, and the mark value is recorded in one of the index areas corresponding to the middle portion of the flash memory.

3. The data recovery apparatus of claim 1, wherein said plurality of logical addresses are consecutive logical addresses.

4. A data recovery apparatus used for a flash memory that includes data areas and index areas in which values indicating whether data stored in the respective data areas are valid are recorded, comprising: a controller that determines whether data respectively stored at a plurality of logical addresses prior to a predetermined logical address, through a data operation, are valid based on a mark value recorded in an index area corresponding to the predetermined logical address.

5. The data recovery apparatus of claim 4, wherein the mark value is recorded in index areas respectively corresponding to first and last logical addresses of the plurality of logical addresses when performing the data operation first on a middle portion of the flash memory and then on other portions of the flash memory, and determining whether data respectively stored at at least one of the plurality of logical addresses between the first and last logical addresses are valid based on the index areas in which the mark value is stored.

6. The data recovery apparatus of claim 5, wherein it is determined whether data stored at the predetermined logical address is valid based on whether data exists at a logical address subsequent to the predetermined logical address.

7. The data recovery method of claim 4, wherein said plurality of logical addresses are a plurality of consecutive logical addresses.

8. A data recovery method used for a flash memory that includes data areas and index areas in which values indicating whether data stored in the respective data areas are valid are recorded, the data recovery method comprising: performing a data operation at each of a plurality of logical addresses; and recording a mark value in a last index area of a plurality of index areas respectively corresponding to the plurality of logical addresses.

9. The data recovery method of claim 8, wherein, in the recording of the mark value, if the data operation is performed first on a middle portion of the flash memory and then on other portions of the flash memory, the mark value is recorded in an index area corresponding to the middle portion of the flash memory.

10. The data recovery method of claim 8, wherein said plurality of logical addresses are a plurality of consecutive logical addresses.

11. A data recovery method used for a flash memory that includes data areas and index areas in which values indicating whether data stored in the respective data areas are valid are recorded, the data recovery method comprising: identifying a mark value recorded in an index area corresponding to a predetermined logical address; and determining whether data respectively stored at a plurality of logical addresses prior to the predetermined logical address, through a data operation, are valid based on the mark value.

12. The data recovery method of claim 11, wherein in the determining operation, it is determined whether the data respectively stored at the plurality of logical addresses are valid based on a mark value recorded in an index area corresponding to one of the plurality of logical addresses where the data operation has performed most recently.

13. The data recovery method of claim 12, wherein, in the determining operation, if the data operation is performed first on a middle portion of the flash memory and then on other portions of the flash memory, it is determined whether data stored in the flash memory are valid based on the mark value recorded in the index area corresponding to the middle portion of the flash memory.

14. The data recovery method of claim 12, wherein it is determined whether data stored at a predetermined logical address is valid based on whether data exists at a logical address subsequent to the predetermined logical address.

15. The data recovery method of claim 13, wherein it is determined whether data stored at a predetermined logical address is valid based on whether data exists at a logical address subsequent to the predetermined logical address.

16. The data recovery method of claim 12, wherein said plurality of logical addresses are a plurality of consecutive logical addresses.

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Flash Memory

DATARECOVERYUNION.COM05 mins

Flash memory is a form of non-volatile memory that can be electrically erased and rewrite, which means that it does not need power to maintain the data stored in the chip. In addition, flash memory offers fast read access times and better shock resistance than hard disks. These characteristics explain the popularity of flash memory for applications such as storage on battery-powered devices.

Flash memory is advance from of EEPROM (Electrically-Erasable Programmable Read-Only Memory) that allows multiple memory locations to be erased or written in one programming operation. Unlike an EPROM (Electrically Programmable Read-Only Memory) an EEPROM can be programmed and erased multiple times electrically. Normal EEPROM only allows one location at a time to be erased or written, meaning that flash can operate at higher effective speeds when the systems using; it read and write to different locations at the same time. Referring to the type of logic gate used in each storage cell, Flash memory is built in two varieties and named as, NOR flash and NAND flash.

Flash memory stores one bit of information in an array of transistors, called “cells”, however recent flash memory devices referred as multi-level cell devices, can store more than 1 bit per cell depending on amount of electrons placed on the Floating Gate of a cell. NOR flash cell looks similar to semiconductor device like transistors, but it has two gates. First one is the control gate (CG) and the second one is a floating gate (FG) that is shield or insulated all around by an oxide layer. Because the FG is secluded by its shield oxide layer, electrons placed on it get trapped and data is stored within. On the other hand NAND Flash uses tunnel injection for writing and tunnel release for erasing.

Although it can be read or write a byte at a time in a random access fashion, limitation of flash memory is, it must be erased a “block” at a time. Starting with a freshly erased block, any byte within that block can be programmed. However, once a byte has been programmed, it cannot be changed again until the entire block is erased. In other words, flash memory (specifically NOR flash) offers random-access read and programming operations, but cannot offer random-access rewrite or erase operations.

This effect is partially offset by some chip firmware or file system drivers by counting the writes and dynamically remapping the blocks in order to spread the write operations between the sectors, or by write verification and remapping to spare sectors in case of write failure.

Due to wear and tear on the insulating oxide layer around the charge storage mechanism, all types of flash memory erode after a certain number of erase functions ranging from 100,000 to 1,000,000, but it can be read an unlimited number of times.

Flash Card is easily rewritable memory and overwrites without warning with a high probability of data being overwritten and hence lost.

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Why flash drive is prone to much more damages?

DATARECOVERYUNION.COM02 mins

Flash DrivesFlash drives have just changed the lives of students, teachers, businessmen, engineers and other working people for their IT jobs. A flash drive comes up with a lot of features including its light weight, small size, portability, reliability, trustworthiness and large storage ability comparable to the existing removable devices. This is a great external storage device – now you can save even a movie or bulk of files in it which was not possible before in punch cards or later in floppy diskette due to their insufficient space of storage.

There are a number of factors which cause for its failure and they don’t allow flash to read and write any data file.

Flash drive is small in size so there are many chances of being misplaced and smashed up going under any heavy gadget.
Flash drives are an easy source of spreading viruses from one PC to the other.
Flash drive can easily be stolen due to its small size.
Extreme temperature may become the cause for destroying its internal circuitry.
Water droplets can also damage flash drive’s functionality.
Data residing in the flash drive can be lost due to its inappropriate removal from computer.
If a flash drive is attached with computer and power fails at the same time then there might be a chance of data loss residing in the flash drive.
Flash contains so many benefits along with number of drawbacks but still it is useful. It is adopted by large number of users.

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What if the Flash Device Is Damaged?

DATARECOVERYUNION.COM03 mins

Data Recovery is always an option for these types of devices. The quality of the recovery depends on how much usable data there is. In the British television program mentioned earlier, after the flash drive was shot out of the cannon and damaged, the producers sent the damaged flash device it to professional data recovery company After working with the device and its pieces, the engineers were able to recover the data on the device and found the data the producers were expecting.

Never assume that the data is gone when physical damage has occurred. The experienced data recovery engineers are capable of repairing complex electronics on USB flash drives.

What about deleted or reformatted USB flash drives? Similar to hard disks, when a USB flash drive is reformatted or data is deleted, the file system addresses to the data are erased—not the data itself. Even if some files are re-saved back to the device, there may be a chance that the information is recoverable. In simple deleted recovery situations, do-it-yourself solutions by using the professional software would be able to find the data and bring it back. In more complex situations where data has been restored back to the device, a trained data recovery engineer would be able to tell the difference between the newly written data and the original data. After an evaluation, the user would know exactly which files sustained damaged and which ones did not.

As long as the flash media is not physically damaged, a quick recovery choice for USB flash drives is that chooses the Remote Data Recovery service from professional data recovery company. The remote engineers can work on your flash drive while it’s still plugged into your computer and has access to the internet or to a modem.

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