Last month, we informed about an error that users began to notice on the popular Samsung SSD drives 840 Evo. A fix of the problem, which manifests a significant decrease in reading performance of the files saved a long time ago, was promised by the manufacturer to be released in the middle of October. The company successfully met the deadline and the fix is already released for download; Samsung has also stated what the cause of the problem was.
The cause of the reduced speed of reading of the old files is probably a software calibration status of each NAND cell, so it is most likely a matter of the firmware. In the course of time the cells undergo a change of their physical characteristics (voltage) and the algorithm readers must adapt to it.
Firmware of the disk 840 Evo wasn’t apparently set accordingly to this logic and the result was that the control unit, when it was reading cells with older files, was detecting errors and so it had to needlessly repeat the attempts, which ultimately lead to the decrease in speed. The new firmware (EXT0CB6Q) should eliminate all of the mentioned problems with the calibration and should also return the expected performance to the storage.
According to Samsung the error should be just in the design of the 840 Evo disk and so shouldn’t be associated with the TLC NAND – type, as we might think. Contrary to some users’ statements, the older type – SSD 840 without the suffix Evo is according to the company also not affected by the problem. A future successor, the 850 Evo, won’t also be affected for it is based on new generation of the TLC memory, which is based on the V – NAND technology
After the loading of the update by the Samsung Performance Restoration tool and rebooting of the system, the disk still maintains the NAND maintenance , which even involves overwriting cells ( this process reportedly requires about 10 % of free space, and it can apparently take about an hour to finish on a 500 GB disk. But it probably depends on the fullness of the disk). This operation (according to the first reactions) actually really restores the original performance of the SSD 840 Evo, nevertheless it is important to keep in mind that the long-term effectiveness of the fix can be confirmed only after some time has passed (after the problematic files are recreated again).
Performance characteristics shouldn’t be changed with the new firmware except for the repaired ones. Although, an update or a subsequent maintenance does not erase data on the disk, you should make a backup of the files, just to be sure (because we can never exclude the problems.)
The repair can be downloaded here. The application has many requirements, so you should read the manual properly. Problems can arise, for example, if you don’t have the newest control unit for an AMD platform or it could possibly be necessary to change the control unit to the AHCI Microsoft system. Furthermore the utility may reportedly not work with RAID, dynamic volumes, encryption, or file systems others than NTFS; disk must be connected to a SATA control unit, not, for example, to a USB converter. In case of similar complications it will probably be necessary to do a manual recovery of the file system after the new firmware is loaded.