Early last month we began to hear reports of Samsung 840 EVO SSD owners experiencing issues with low read speeds of data that had not been touched/moved for an extended period of time after being written. In most cases, this data had been present in the flash memory for a period of weeks or months. As time went on, reads of this older data would continue to slow further, even as low as 50-100 MB/s. For what it is worth, we are not aware of any situations where users suffered data loss – merely slow read performance.
Samsung recently released the following statement concerning this loss of read speeds on the 840 EVO series of SSDs:
“We acknowledge the recent issue associated with the Samsung 840 EVO SSDs and are qualifying a firmware update to address the issue. While this issue only affects a small subset of all 840 EVO users, we regret any inconvenience experienced by our customers. A firmware update that resolves the issue will be available on the Samsung SSD website soon. We appreciate our customers’ support and patience as we work diligently to resolve this issue.”
Our friends over at PC Perspective got involved early on, and ended up working hand-in-hand with the Samsung support team to identify the source of the problem, and to test and verify the firmware update prior to its release to the public. Here is Samsung’s statement about the specifics of this issue:
“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.”
Allyn Malventano over at PC Perspective has done some excellent research and analysis of this issue, and has been the lead contact working with Samsung to address and fix the performance degradation problem. His article from 10/14 is well worth reading for anyone interested in the details of studying the problem and testing the firmware update before its release into the wild. Allyn’s theory was that the slow down was due to cell voltage drift over time. Here is his graph depicting the variance:
Although it was not yet available when we started this article, we did finally find a link to the Samsung 840 EVO firmware update in a discussion forum. Highlights of the firmware update follow:
SAMSUNG SSD 840 EVO PERFORMANCE RESTORATION v.1.0
First and foremost, back up any important data before attempting the update. This firmware update applies to both 2.5″ and mSATA form factors of the 840 EVO. This update supports both Microsoft and Intel drivers for Intel chipsets. For AMD chipsets, Microsoft, AMD and Nvidia drivers are supported. Please note that only the latest AMD driver version is supported. For AMD driver users, it is imperative that you update to the most current version prior to attempting the firmware update to avoid error messages and a failed update.
The update download is a zip file that includes both the firmware update executable and an installation guide in pdf format. The installation guide includes two installation modes — normal and advanced. Normal mode is for drives with more than 10% free space. Normal mode will encompass the vast majority of users. Advanced mode is for drives with 10% or less free space. Advanced mode requires the user to remove/delete unused and/or unneeded files and programs until more than 10% free space is achieved. Once this has been accomplished, the update proceeds the same as in normal mode.
The various screens you will encounter include:
Step 1: Start Performance Restoration
Step 2: Update Firmware
Step 3: Restoration is in Progress
Step 4: Restoration is Complete
10% or less free space warning:
Samsung has also indicated that they should be releasing an ISO/DOS version of the performance restoration tool at the end of October for MAC and Linux users.
It is always encouraging to see manufacturers such as Samsung step up and resolve such issues quickly. It is also gratifying to see them work closely with tech reviewers and the tech media to identify the problem and get it resolved. Here again is the link to the Samsung 840 EVO firmware update download.