I just found that the specs of server harddisks mention a maximum number of TB read. For example WD Black Drive 2 TB mentions a 550 TB transfer limit per year. This means that every day it should read it's entire context only 1.5 times.

Is there a real limit or is it just a heuristic to guess heavy disk usage and nullify the 5 year warranty?

My usecase is strict serial reads over the whole disk (bare metal like dd does) to process big data - emulating some Tape Library access. I would guess this is a more healthy scenario then random access. Correct, irrelvant or wrong?

  • "For example WD Black Drive 2 TB mentions a 550 TB transfer limit per year" - can you link to where this is stated so we can see the context, please? – TessellatingHeckler Mar 14 '14 at 17:47

Some Western Digital drives comes with a "recommended workload". Examples of this can be found on some of their product spec sheets

Designed to handle up to 550 TB per year

This isn't a hard limit but, is a recommended design limit based on their claim based on their testing that failure is linearly tied to total data transfer. I don't believe it would void the warranty and I don't believe they would have any means to validate the total data transfer of the drive anyway. While many manufacturers use the MTTF (Mean Time to Failure) metric, WD has started to use a MPbF (Mean Petabytes to Failure) metric which is tied to the recommended workloads of their drives.

Western Digital wrote a white paper to defend their stance titled: Why Specify Workload? if you wanted to read their explanation on why they are choosing to use this metric.

In conclusion, MTTF alone is insufficient to fully describe the field reliability of HDDs. This results from the fact that HDD failure rates are more tightly coupled to the total amount of data transferred rather than the total power-on-time. In order to more fully characterize the quality level of HDDs, WD will now specify both the MTTF and the maximum workload at which the MTTF will be met in the field

  • Interesting paper. So the only problem is that during read/write operations the head is closer to the surface increasing the danger of head crashs. It has nothing to do with the read/write patterns. This is a serious challenge for my business model :-( – Lothar Mar 14 '14 at 19:05

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