Mark Hahn wrote:
In contrast, ever since these holes appeared, drive failures became
the
norm.
wow, great conspiracy theory!
I think you misunderstand. I just meant plain old-fashioned
mis-engineering.
I should have added a smilie. but I find it dubious that the whole
industry would have made a major bungle if so many failures are due to
the hole...
But remember, the google report mentions a great number of drives
failing for
no apparent reason, not even a smart warning, so failing within the
warranty
period is just pure luck.
are we reading the same report? I look at it and see:
- lowest failures from medium-utilization drives, 30-35C.
- higher failures from young drives in general, but especially
if cold or used hard.
- higher failures from end-of-life drives, especially > 40C.
- scan errors, realloc counts, offline realloc and probation
counts are all significant in drives which fail.
the paper seems unnecessarily gloomy about these results. to me, they're
quite exciting, and provide good reason to pay a lot of attention to
these
factors. I hate to criticize such a valuable paper, but I think they've
missed a lot by not considering the results in a fully factorial analysis
as most medical/behavioral/social studies do. for instance, they bemoan
a 56% false negative rate from only SMART signals, and mention that if
40C is added, the FN rate falls to 36%. also incorporating the
low-young
risk factor would help. I would guess that a full-on model, especially
if it incorporated utilization, age, performance could comfortable
levels.
The big thing I notice is that drives with SMART errors are quite likely
to fail, but drives which fail aren't all that likely to have SMART
errors. So while I might proactively move a drive with errors out or to
non-critical service, seeing no errors doesn't mean the drive won't fail.
I haven't looked at drive temp vs. ambient, I am collecting what data I
can, but I no longer have thousands of drives to monitor (I'm grateful).
Interesting speculation: on drives with cyclic load, does spinning down
off-shift help or hinder? I have two boxes full of WD, Seagate and
Maxtor drives, all cheap commodity drives, which have about 6.8 years
power on time, 11-14 power cycles, and 2200-2500 spin-up cycles, due to
spin down nights and weekends. Does anyone have a large enough
collection of similar use drives to contribute results?
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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