The article discusses the impact of high absolute temperature on the longevity of drives, however from my amateur knowledge the range of temperature during a day is also an important factor.
I always assumed that having a stable 40°C is better than a drive constantly swinging between 20°C and 40°C, so I am surprised that the article only mentions alerts on reaching a high threshold.
Andy Klein from Backblaze here. Your point is a good one in that temperature fluctuation can be an important factor. We actually sample smart stats, which contain the temperature attribute, multiple times a day looking for such changes. The Drives Stats data is captured once a day, so it looks static, but behind the scenes the monitoring is more dynamic.
Do you have plans to look at whether higher fluctuations translate into higher failure rates? Not sure whether you have historical data on this, but I would be really interested in this aspect, even if you can only run the stats on a smaller number of drives or shorter time periods.
Maybe dividing the drives roughly in "higher than average variability" and "low variability" and then looking at the AFR for this subset can show some relation. Of course as the AFR for many drives is already quite low, the effect might be too small to distinguish from noise.
On the topic of temperatures: Have you run an analysis whether a drive increasing in temperature (or maybe even decreasing) compared to its base line and "neighbors" results in a higher chance of failure?
I always assumed that having a stable 40°C is better than a drive constantly swinging between 20°C and 40°C, so I am surprised that the article only mentions alerts on reaching a high threshold.