Compared to tried-and-true magnetic storage, SSDs are still finding their feet. And like all technologies, it can be hard to predict the issues that might pop up after long-term use without, you know, using them long-term. Take for instance Samsung, which is discovering just now that its 840 EVO series of SSDs have a bug that cripples read performance, but requires at least one-month old data on the drive before the problem appears.
As Kristian Vättö over at Anandtech explains, the read performance bug is well-documented on many popular tech forums across the web. The consensus is that the poor read speeds are caused by "old blocks of data", which unless you're constantly reformatting or using your SSD as a glorified cache, affects pretty much anyone using the drive. "Old" in this case means a month or more, so if you own an 840 EVO, it's likely you're drive isn't running at its best.
Fortunately, if the problem is firmware-related -- that is, the drive's internal software is at fault -- a fix in the form of a simple update from Samsung is all that's required. According to Vättö, that's exactly what the company is currently working on:
I just got off the phone with Samsung and the good news is that they are aware of the problem and have presumably found the source of it. The engineers are now working on an updated firmware to fix the bug and as soon as the fix has been validated, the new firmware will be distributed to end-users. Unfortunately there is no ETA for the fix, but obviously it is in Samsung's best interest to provide it as soon as possible.
This isn't the first time an SSD has revealed its uglier side only after an extended period of use. Crucial's M4 series had a bug that effectively rendered the drive useless after 5200 hours of use, though it was corrected via newer firmware.
Just to be clear, this bug only affects the 840 EVO, not newer drives such as the 850 Pro we reviewed earlier this year.