Mailinglist Archive: opensuse (982 mails)

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Re: [opensuse] Re: Interpretation please
On Mon, 01 Sep 2014 21:13:26 -0700
Linda Walsh wrote:

Nope... It really is the raw error read rate... It matches up exactly
with the Hardware ECC correction rate. All of the raw errors are
currently being corrected by ECC. When they aren't, you'll start
seeing sector remapping, which is when you start to really notice
disk slowdowns --- they prevent contiguous reads.

I don't know how long one can use ECC to get by with, BUT I've always
been told it's the first step towards an unreadable sector that gets
remapped.

Well, this technology has come a long way in 20 years. Here I've been,
minding my own business, operating on the background assumption that
S.M.A.R.T. _now_ is pretty much what it was back then -- maybe with
more 'bells and whistles' accrued over that time.

My understanding from when I delved deeply into it (I was working in
the storage products industry, btw, in Silicon Valley) was that 'raw
read error rate' and 'seek error rate' related to 'cache misses' not
actual, physical read errors. My understanding was that these metrics
were being used statistically, internally, over long periods of time and
across a massive install base by the manufacturers to monitor and
improve caching algorithms.

In Seagate's own words*: "The idea ... is to predict a failure before it
happens. Various attributes are being monitored and measured against
certain threshold limits. If any one attribute exceeds a threshold then
a general SMART Status test will change from Pass to Fail." and "The
individual attributes and threshold values are proprietary and we do
not offer a utility that will read out the values." Finally, "As a
practical matter, the technology supporting SMART is constantly being
improved. Each new design incorporates improvements that increase the
accuracy of the SMART prediction. As a matter of policy, Seagate does
not publish attributes and thresholds. Therefore, if you wish to test
the drive for physical integrity, please use our SeaTools diagnostic
software."

From a practical standpoint, a 'fail' in lieu of a 'pass' with a drive
that remains operational, under warranty, is sufficient to obtain a
warranty replacement drive from Seagate.

In the OP's specific case, if the attribute 'reallocated sector count'
is correct for both drives, they're at zero (0). All things being
equal, between that and SMART test 'pass' would give me a fairly high
degree of confidence that failure doesn't seem to be imminent. I'd
still, as I always do, back up my important data.

(*) <http://knowledge.seagate.com/articles/en_US/FAQ/203971en>

regards,

Carl
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