The only difference between the drives I could think of is that the data on this slow drive was written a couple of years ago and has been almost untouched since then, and has been accessed very rarely. So my thoughts are the slow read speeds could be to do with the charge in the NAND cells running low over time.
I actually tested this theory by copying fresh data onto the drive and then measuring the speed when copying this fresh data to another drive. The speeds were very fast, 2000MB/s+, as I expected. So I think this theory is correct.
Anyway, I ran a surface read test and this showed a strange cyclic pattern in the read speeds. I don't know if this is anything to worry about? I thought it may be the SLC cache on the SSD filling up, but the read speed during this part of the test was less than 100MB/s, so I can't imagine that is the issue.
To investigate more, I am now running a Read + WRITE + read test to see if this can "fix" the slow read speeds for the data. However, it is now showing many bad blocks with the error:
Code: Select all
Error: 23 Data error (cyclic redundancy check)
SMART info shows no errors and full health for the drive.
It's worth noting that my data is already backed up in multiple locations so I have no concerns about losing the data on this drive.
Screenshots are below. What should my next steps be? Should I be concerned that the drive is failing? Should I reinitialise the disk? Is there any point letting this current test complete? It's taking a long time...
Surface read test:
Surface read test speeds and temps:
Surface Read + WRITE + read test: