Backblaze lists the most reliable hard drives of 2021

Backblaze, the cloud storage provider, recently published its 2021 annual report about the performance of 202,759 operational hard drives.

The company uses drives of multiple capacities and ages, from brands such as Seagate, Toshiba, HGST, and WDC, while monitoring each model’s annualised failure rate or AFR, calculated using the following formula [AFR = (drive failures / (drive days / 365)) * 100].

This report is important as it provides a glimpse into the reliability of hard drives, pitting one manufacturer against another, and Backblaze goes further by breaking down each model into capacity, the number of drives examined, average age, and most importantly, failure. Being mechanical spinners by nature, SSDs are not taken into account.

The report indicates that AFR for all operational drives rose to 1.01 per cent in 2021, up from 0.93 per cent in 2020, although still below the 1.83 per cent of 2019. This is thanks to new high-capacity drives that account for 69 per cent of Backblaze‘s active catalogue, whilst only contributing to 57 per cent of the overall failure rate. In other words, newer drives are less likely to fail than older ones, which stands to reason.

Seagate’s 6TB ‘ST6000DX000’ is still the most reliable drive in the arsenal, with an AFR of only 0.11%, even though they are 80.4 months old on average. Perhaps the comparatively limited quantity of just 886 helps in this regard.

On the opposite side there is the 14TB Seagate ‘ST14000NM0138’, which has an AFR of 4.66 per cent in Q4 of 2021, down from 6.29 per cent in the previous quarter. Backblaze mentioned that 19 drives of this model that failed in Q4 were shipped off for further analysis, and that it’s continuing to follow this process over the coming quarters.

In the end, keep in mind this is not an indication of the general reliability of any specific brand, but it gives us an overview of how different capacities and technologies fare against one another.

It is actually more important to select a particular model than brand, as Seagate ably demonstrates with AFRs of 0.11 and 4.79 per cent on two families. Overall, Western Digital does well by having a maximum AFR of 0.43 per cent.