Re: 3TB drives failure rate

[Ed W <lists@wildgooses.com>]

On 28/10/2012 12:15, Rainer Fügenstein wrote:
> when trying to upgrade my raid5 with 4 Western digital caviar green
> 3TB drives [WDC WD30EZRX-00MMMB0] (3 brandnew, 1 about 4months old),
> the "old" drive and one of the brand new ones failed with
> unrecoverable read errors and about 70 reallocated sectors each. the
> failures already occured during the initial resync after creating the
> raid.
>
> until now I was very fond of WD caviar green drives, but after this
> 50% failure rate I'm not very eager to restore data from the backup.
>
> what is your experience with 3TB drives, WD and others?
>
> (low power drives appreciated, performance is not an issue)
>

I think there is clearly serial correlation in drive failures and this 
tends to cause people to have brand love/hate stories.

I bought 9x Samsung 2TB green things about 2 years back  (to go in an 8x 
NAS + 1 spare).  I think I had to return 4 almost immediately due to 
either out of box reallocation warning, or that appeared within 2 
weeks.  Probably if I hadn't been looking I wouldn't have noticed these 
warnings and then been one of those groaning about Samsung when probably 
they all expired within a few weeks of each other.  The RMA'd drives 
have all been fine and the whole array seems ok some years later (tested 
weekly).  Note that I think I got 2x drives from a different supplier 
(hence different batch), so that implies something like 4 out of 7 in a 
given batch were "worrying", but the next 4 from a new batch showed no 
obvious problems

I think this fits with the idea that the spinning disk failure curve has 
a bump in the first few weeks, then flat until some years later when it 
peaks again...

My conclusion:
- RAID6 for data that is highly valuable (and performance is acceptable)
- Thrash the drives initially for some weeks before you accept them into 
production.
- Although highly debated, I believe that failures are likely to be 
correlated in time, when one drive goes there is a high probability of 
loosing others in the next 24 hours. Take precautions as you see fit, eg 
regular backups, hot/warm spares, etc
- Green consumer drives likely are satisfactorarily reliable for most 
uses, caveat that you accept they will fail catastrophically eventually 
(just like your enterprise drive will).  We can debate the relative life 
of each, but it's almost certainly just a linear factor...

Good luck

Ed W

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