November 30, 2010 at 08:13Flash memory SSD, SD, MMC, etc. Recovery and repair
Recently, various devices using flash memory have been used to store data. These are compact, fast and shock-free devices.
But from the point of storage and reading of information on flash memory, there are four main problems:
- low write speed to the cell;
- a limited number of write cycles per cell (for mlc: 10,000 times, for slc: 100,000 times);
- reducing the time of static storage of data depending on the number of write cycles;
- charge draining over time (∼2 year).
To partially address these shortcomings, it is necessary to allocate part of the flash memory for service data and use a special controller. This controller, using overhead data, controls the number of records in the memory cell, the validity of user data, and also implements a complex block-mode write-read of memory cells to increase performance. This work ensures the integrity and reliability of user data. But there are times when the service data itself is violated. In this case, a translation violation (violation of the sequence of readable memory cells) occurs. With such malfunctions, access to the logical structure of flash devices is violated - the device either cannot be seen, or shows the wrong volume, or it can only be accessed in read mode.
Repair of such drives is possible if the data that is on the faulty device is not important. Features of the repair and software for this can be found on the site: Utilities and firmware (the link has been changed for dumb;) ... I have no relation to the site)
But if you need to restore data, then you will encounter a completely non-trivial task, comparable in level of complexity with restoration complex devices like RAID arrays. During data recovery, a flash memory chip is removed from the faulty device, data cells are read from it, and using special programs, data is restored.
In what other cases do you have to resort to data recovery from flash devices?
It is also necessary to resort to the data recovery operation described above for physical (electrical) damage to the controller of a flash device, as well as for fakes from Southeast Asia, which usually mimic flash devices with a larger amount of memory than in reality. Such devices usually work normally until the amount of recorded data exceeds the actual volume of the device.
But from the point of storage and reading of information on flash memory, there are four main problems:
- low write speed to the cell;
- a limited number of write cycles per cell (for mlc: 10,000 times, for slc: 100,000 times);
- reducing the time of static storage of data depending on the number of write cycles;
- charge draining over time (∼2 year).
To partially address these shortcomings, it is necessary to allocate part of the flash memory for service data and use a special controller. This controller, using overhead data, controls the number of records in the memory cell, the validity of user data, and also implements a complex block-mode write-read of memory cells to increase performance. This work ensures the integrity and reliability of user data. But there are times when the service data itself is violated. In this case, a translation violation (violation of the sequence of readable memory cells) occurs. With such malfunctions, access to the logical structure of flash devices is violated - the device either cannot be seen, or shows the wrong volume, or it can only be accessed in read mode.
Repair of such drives is possible if the data that is on the faulty device is not important. Features of the repair and software for this can be found on the site: Utilities and firmware (the link has been changed for dumb;) ... I have no relation to the site)
But if you need to restore data, then you will encounter a completely non-trivial task, comparable in level of complexity with restoration complex devices like RAID arrays. During data recovery, a flash memory chip is removed from the faulty device, data cells are read from it, and using special programs, data is restored.
In what other cases do you have to resort to data recovery from flash devices?
It is also necessary to resort to the data recovery operation described above for physical (electrical) damage to the controller of a flash device, as well as for fakes from Southeast Asia, which usually mimic flash devices with a larger amount of memory than in reality. Such devices usually work normally until the amount of recorded data exceeds the actual volume of the device.