Today SSD and Flash storage devices have large storage space and fast read / write high . But , unfortunately , the reliability and durability of the device based on non-volatile NAND memory is deteriorating every year . Thus , the problem of data recovery from corrupted SSD and other devices with NAND memory is becoming more consistent and needs on the world market .
Each solid-state drives , USB pendrive or memory card consists of two main components - the controller chip and NAND memory chips . Endurance of the memory chip in the last few years has decreased tenfold . The memory cell of SLC chips can withstand around 100,000 write cycles , 10,000 write cycles for MLC , and TLC 500-1500 latest write cycles . As the number of corrupted memory cells ( blocks ) exceeds the limit , the data storage device failed and access to user data becomes impossible. The controllers used in flash storage devices are working in extreme temperature conditions and often get damaged .
The controller chip controller read / write operations , optimize data in memory chips and not stop maps ( liquor ) using a special algorithm liquor , all of this is called FTL ( Flash translation Layer ) . Each controller manufacturer uses a different algorithm liquor with the different steps of data optimization . Thus, in case of damage solid -state drives , especially when the controller chip is damaged , lost data access . Even so , the data is still stored inside the memory chip . The only way to recover the data in this case is desoldering and subsequent reading of the memory chip . After receiving yards of memory chips , need to apply for special operations to bring data to its original state - to eliminate the effect of data optimization and the application of the algorithm liquor control . Therefore , the process of data recovery consists of several steps that allow the simulation of the controller operation and reconstruct the file system with user data :
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Memory chip desoldering
Memory chip read
Removing optimize data ( combined data )
Block translation algorithm ( PBA - LBA )
Desoldering process memory chips are made using soldering station with hot air gun . For the latest chip as TLC it is recommended to use a soldering iron to avoid overheating of the crystal , because this determines the number of read errors and data integrity . When desoldering BGA chip as TLGA52 , BGA100 Product , BGA152 and others , especially the tower heat exchanger is required .
The process of reading and further analysis chip memory dump is performed with the use of special equipment for data recovery . Each NAND chip readers use different configurations , depending on the model . In the process of reading some errors may appear due to noise and physical characteristics of the chip are made of nho.Khi read error correction required by the specific mathematical algorithms , such as Reed - Solomon , BCH , LDPC .
Before writing the data to the control chip memory , data is optimized . This process alters the original data and make it unrecognizable . This optimization process can include activities such as Byte division , Inversion , XOR encryption , encryption , interleaves , etc. To get the original data is necessary to apply the reverse operation to dump of the memory chip .
When all the required data conversion is done it is necessary to apply the algorithm liquor will sort all the data blocks according to their actual position . The result of this algorithm is an image of the data to the file system .
If the solid state drive file system corruption due to errors of control then continued recovery may reasonably be required of the system image file .
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