Unfortunately that didn’t work out as planned, and while the data refresh from the performance restoration tool did bring drive performance back up, over the long run performance once again began decaying on old data, even with the firmware improvements.
The idea being that fresh data in combination with the newer firmware would prevent the drive’s performance from decaying again. The combination of the tool and firmware would update the drive to better handle decayed cells and reduce the need to re-read them, meanwhile the restoration tool would refresh the drive’s data by re-writing all of the data to fresh cells. At the heart of the issue was the drive’s relatively uncommon 19nm TLC NAND, which given the combination of small feature size and tighter requirements of TLC, eventually resulted in the drive having to slow down and re-read cells to properly read the charge-decayed cells.Īiming to fix the issue, in 2014 Samsung released a performance restoration tool and firmware update for the 840 EVO.
After initially launching in 2013 to great fanfare as an excellent, strong-performing low-cost drive, over the long run performance regressions began to occur in deployed drives that saw the read performance of old data significantly drop. If nothing else, the odyssey of Samsung’s 840 EVO has not been lacking in excitement.
