On Thu, 2014-06-05 at 08:44 -0500, Richard R. Pope wrote:
> David,
>      That makes me wonder if that company has another under lying=20
> problem with their system. If their drives fail after six  months or so=20
> maybe there is a power supply or cooling problem. Hum, just a thought.

The problem is their application writes 24/7.  The SSDs are part of a
storage array that services dozens of small ARM systems.  Senaca hosts
the build system for the Fedora distribution for ARM.  Fedora has
somewhere north of 15,000 packages, releases every six months, and it
takes lots of builds for a release.  Fedora rules require that the
packages be compiled on the target system, hence no cross-compiling
which would be a lot faster.  Compiling 15,000 packages on a Beagle
Board takes some time, hence the large number of systems.

They don't see reliability issues with magnetic drives, but in their
application, the performance improvement is worth the cost.  Obviously,
being a university they ran the tests, did the math, and the SSDs won,
even though they have a limited life.  And they don't wait for failures.
They remove them from service before they are expected to fail because
they don't want the downtime.  They also tested a number of
manufacturers a couple years ago, I don't know whether they have gone
back and re-run the tests with more recent drives.  They did a
presentation at FUDcon Blacksburg, I suspect a video might still be
online.

If you recall, back in the PIC16F84/84A, 628/628A days there were some
pretty dramatic differences in flash life between different PICs.  Seems
like there is a tradeoff between life, speed and manufacturing cost,
although I'm not familiar with the manufacturing process in any level of
detail.  But some PICs had 100 or 1000 times the flash life of others,
and it wasn't always the newer PICs with the longer life.  But then,
number of flash writes isn't that big a deal with PICs - even a hobbyist
is unlikely to program a particular PIC 1000 times, and I seem to recall
most were in the 10,000 to 100,000 write range.

--McD


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