As reported several weeks ago, a number of users (including yours truly) were experiencing slow read performance issues with their Samsung 840 EVO SSD. At the time, the issue was just discovered by various Samsung 840 EVO owners and Samsung was still working on a fix to the issue. As of yesterday, Samsung provided us with an early firmware update that appears to help fix the issue.


Here we can see performance figures from the drives before and after. Before the fix (left), performance was slow and inconsistent. After the fix, performance is back up to normal. Of course, it does take some time before the performance issue pops up, but the results seem positive so far. We’ll be further testing these drives in the weeks to come.

The performance fix is expected to be available sometime tomorrow and we’ll be sure to update this article with where you can download it.


Samsung SSD 840 EVO Performance Restoration

Samsung’s utility for fixing the 840 EVO is aptly named Samsung 840 EVO Performance Restoration. It’s actually a separate utility from the Samsung Magician software and is specifically designed as a performance fix for the Samsung 840 EVO.

The utility works in two steps.


In the first step, the utility updates the firmware on the drive to firmware EXT0CB6Q.


Then in the second step, the utility appears to rewrite all the data on the drive using a new algorithm. This step will take a substantial amount of time depending on how full the drive is, so definitely set aside some time for this fix. Although this fix shouldn’t be destructive, I’d definitely advise backing everything up prior to updating.


FAQ (Frequently Asked Questions)

Samsung also provided us with answers to some frequently asked questions regarding the issue and the performance fix.

What is the problem?  How does this “fix” resolve the problem?

  • Because of an error in the flash management software algorithm in the 840 EVO, a drop in performance occurs on data stored for a long period of time AND has been written only once. SSDs usually calibrate changes in the statuses of cells over time via the flash management software algorithm. Due to the error in the software algorithm, the 840 EVO performed read-retry processes aggressively, resulting in a drop in overall read performance. This only occurs if the data was kept in its initial cell without changing, and there are no symptoms of reduced read performance if the data was subsequently migrated from those cells or overwritten. In other words, as the SSD is used more and more over time, the performance decrease disappears naturally.  For those who want to solve the issue quickly, this software restores the read performance by rewriting the old data. The time taken to complete the procedure depends on the amount of data stored.

Is my data at risk?

  • The error only results in a drop in read performance, and there are no issues related to data loss or drive reliability.

Is the “fix” a firmware fix?  If yes, why isn’t it being managed through the traditional SSD Magician firmware management process?

  • Resolving the performance issue requires both a firmware fix and performance restoration process, which Samsung has provided a special tool.  This tool will execute the performance restoration process and upgrade to the latest firmware (EXT0CB6Q).  Future firmware releases will continue to be supported through Samsung SSD Magician.

Does the problem affect all versions of the firmware?  EXT0BB6Q? EXTOAB0Q?  EXTOBB0Q?

  • Yes

Is Samsung recommending all consumers perform this “fix” or only consumers that are experiencing a problem?

  • Samsung recommends users perform the upgrade only if they’re experience a problem.

What was changed about the newly shipping drives to prevent this from happening in the future?  What date did the “fix” get implemented for newly shipping drives?

  • New production units have the latest firmware (EXT0CB6Q) which will not experience the performance slowdown.  In addition, all new drives experience additional performance qualification prior to shipping.  All product shipped from the factory after October 1st contains the latest firmware (EXT0CB6Q).

Because the problem only occurs on “old” data, will this “fix” need to be run periodically?  If not, why not?

  • Once the old data is moved via the performance restoration process, the cell status is stabilized and consequently, no future calibration is required.

Does it affect the 840 EVO mSATA?  If yes, will this “fix” work on the 840 EVO mSATA?

  • Yes. The performance restoration software covers the mSATA models also.

Does this problem affect the 840? 830?  840 PRO?

  • No.  The problem only occurs on the 840 EVO.


Update 10/15/2014

The Samsung 840 EVO Performance Restoration software is now available at the Samsung website here. The update is currently available to Windows users only, but a Dos version for MAC and Linux users is expected to be available at the end of the month.