I have a Seagate ST9750420AS HDD in my laptop, which I have been using for the last couple of years. I recently realized that the disk was noticeable slower than before, so I decided to check the SMART data.
Everything seemed to be OK. A bit more than a year powered on, head flew for 11 months… and all the read errors successfully corrected; no big deals. I decided to note anyway the read error rate, which had a value of 60M (normalized 119, threshold 6, worst 99).
Today (3 days after), I checked again those numbers and the read error rate value is at 215M, which seems to me like a huge increase in a little time. The normalized and worst values haven't changed anyway, so the assesment is still OK in the SMART data.
Should I be worried? My data is backed up, but should I be already buying a new HDD for my laptop?
Best Answer
After some time, I can confirm that the raw read error rate value isn't very meaningful nor reliable. I have seen this counter reset to 0 more than once since I posted this question. And although the normalized value has decreased, it is still way above the threshold.
The reason why I posted this question was because I started to realize that the HDD was noticeable slower than before. Opening the file manager could take even seconds, as well as opening other programs or files. And I could hear the HDD "struggling" and making noise as trying so hard to read just a couple of bytes (and could see the raw read error rate increase a lot just after any of those operations...). Formatting didn't help with that anyway. Ensuring the HDD was correctly connected and the connector was clean didn't help either.
Why was this happening? I don't know, but I ended up buying a small SSD to replace it and use the HDD as a secondary drive (for data only). That increased my productivity at work and my health too... :-P (hearing my HDD struggling for reading data was making me sick)
As a conclusion: the raw read error rate is not meaningful by itself. The HDD seems to be working fine still, and it will probably continue to work for another couple of years, although it continues to be slow (something that does not bother me while the OS is on another disk).
My personal recommendation: always make backups even when your disks are healthy and brand new. If you feel your HDD is getting slow, consider buying a SSD to put your OS on it. They are pretty affordable nowadays and, if you use your computer a lot (i.e.: you work full time with it), then you'll really notice the difference.