is 3.5 or 2.5 HDD more durable (less likely to fail soon)?

[kenny1999]

I am thinking about buying either 3.5 desktop external or 2.5 portable hard drive. Regardless of the price, size and portability, (I can skip using outside), which one is more durable (i.e. less likely to fail quickly , I know it must fail one day)?

[newpball]

In simple terms if you are worried about it your backup scheme is inadequate!

Always assume your hard drive will crash tomorrow!

If you have at least one copy of your important data on another media at any time you can relax.

[pandy]

I am thinking about buying either 3.5 desktop external or 2.5 portable hard drive. Regardless of the price, size and portability, (I can skip using outside), which one is more durable (i.e. less likely to fail quickly , I know it must fail one day)?

2.5 should be more robust - smaller and lighter + features used in portable equipment.

[Krispy Kritter]

In regards to actual hardware failures, both types should be equal. This would be more a matter of brand/quality, than drive type.

[nic2k4]

Doesn't look like there's any official statement on comparing the reliability of both drive type. Seems like drive makers no longer believe in the quality of their products, they no longer use MTBF to rate reliability. I found some datasheets for drives from the same year (2009) and though MTBF is a measure of reliability it's not representative of what happens in reality as Krispy Kritter mentions.

3.5" MTBF 700,000 hours (page 18)

2.5" MTBF 500.000 hours (page 2)

[newpball]

Seems like drive makers no longer believe in the quality of their products, they no longer use MTBF to rate reliability.

You seem to imply that those things are related (believing in quality and providing MTBF data), that is simply not true. MTBF for instance tells you nothing about reliability. AFR does, and reporting AFR is now the standard.

[nic2k4]

Is AFR a better measure of reliability than MTBF? I don't know, but it certainly is less subjective (obfuscate?). Personally I prefer MTBF and for some odd reason (marketing) even WD thinks it's better for their SSD's. Besides, MTBF is an important factor in measuring AFR.

[pandy]

Truth is more complex.
From physical perspective 2.5 inch units are more robust, also internal quality vendor is important - seem that Hitachi leads (lower failure ratio than other brands) when failure data are analyzed.
https://www.backblaze.com/blog/hard-drive-reliability-update-september-2014/

"The good news is that the chart today looks a lot like the one from January, and that most of the drives are continuing to perform well. It’s nice when things are stable.

The surprising (and bad) news is that Seagate 3.0TB drives are failing a lot more, with their failure rate jumping from 9% to 15%. The Western Digital 3TB drives have also failed more, with their rate going up from 4% to 7%."

So first consider to buy Hitachi, then WD and at the last Seagate - at least when reliability is important for you.