Predicting an exact lifespan under non-ideal storage conditions is challenging, but here are some factors to consider:
• Normal Drive Lifespan: Under ideal conditions (cool, dry environments) many modern HDDs will reliably retain data for 10–20 years. However, manufacturers’ warranties are often only 2–5 years because they consider factors like mechanical wear during active use—not long‐term archival storage.
• Temperature Impact: At 36°C (97°F), you’re well above the typical recommended storage temperature (usually in the 5–25°C range). Elevated temperatures can accelerate magnetic decay and chemical degradation of the media. Magnetic coercivity (the ability to retain magnetization) is affected by temperature, and while complete demagnetization is generally a slow process, the increased temperature can hasten the loss of magnetic stability.
• Humidity Impact: Humidity levels of 58–68% are on the high side for archival storage. Excessive humidity can contribute to corrosion of the magnetic media and other internal components, potentially leading to data errors and physical degradation (bit rot).
• Duty Cycle: Energizing the drive only once a year is somewhat unusual. While infrequent power-on might reduce mechanical stress, modern drives often rely on self-monitoring, error correction, and periodic refreshing of data (in some archival systems) to preserve integrity. Without regular use or proper “refresh” cycles, the reliability of the stored data may suffer over time.
Given these factors, if a 2.5" HDD is stored in an environment with 36°C and 58–68% humidity and is only powered on once a year, you might see significant degradation (such as bit rot or degradation in magnetic signals) in a shorter timespan than ideal conditions. Some estimates suggest that under such adverse conditions, you could start encountering issues in as little as 5–10 years, rather than the 10–20 years possible under cool, dry storage. However, “demagnetization” in the sense of total data loss is typically a very gradual process—bit rot or read errors can occur well before the drive is completely demagnetized.
In summary, while exact timing isn’t guaranteed, under these conditions you should plan on a significantly reduced useful lifespan (perhaps around 5–10 years) compared to a drive stored in optimal conditions. Always consider making multiple backups and migrating data periodically if long-term archival storage is required.