What happened to read error rate on my 7 month old WD HDD? Is this a concern?

Solution 1:

"Normalized value", commonly referred to as just "value", is a most universal measurement, on the scale from 0 (bad) to some maximum (good) value.

Maximum values are typically 100, 200 or 253. Rule of thumb is: High values are good, low values are bad.

In your case, the values of 100 and 200 only meant that there was yet no meaningful data, as the disk was new.

After 7 months, some of the values have changed and now have meaning beyond the meaningless "100" or "200".

You should be happy to see that "Read Error Rate" is still unset, meaning that your disk had no errors and is in good shape.

See ZAR - Quick guide to understanding S.M.A.R.T. information.

Solution 2:

"T.E.C." (Threshold Exceeded Condition) is the alert condition when any parameter falls below threshold.

All the thresholds use inverse logic. i.e. going <= threshold is a failure. But RAW data is cumulative but inverted into something and rounded off as ratio.

So error rate is counting (Terra or Penta) bytes transferred (rounded exponents) between burst errors before ECC hardware error correction code (ECC) is invoked.

So the threshold triggers are inverted to what (You & I) thought they meant.