Is SMART really that dumb?

Robert Nichols rnicholsNOSPAM at comcast.net
Sun Mar 15 15:40:22 UTC 2015


On 03/15/2015 10:23 AM, Chris Murphy wrote:
> On Sun, Mar 15, 2015 at 8:54 AM, Robert Nichols
> <rnicholsNOSPAM at comcast.net> wrote:
>
>> One thing I noticed in there is:
>>
>>    193 Load_Cycle_Count        -O--CK   001   001   000    -    747412
>>
>> That drive is absolutely _killing_ itself by unloading the heads every
>> 90 seconds or so (17421/747412 = .0233 hours/cycle).  This probably
>> isn't related to the problem you're seeing, but you should look into
>> what timeout setting is causing that.  It's hurting performance, too.
>
> While it seems pathological, I'd leave it alone if the drive is being
> used for the proper workload it was designed for. The less time the
> heads are flying over platter surface, the better. Even though this
> attribute value is 001 and the threshold is 000, it's not a pre-fail
> attribute, just an age attribute. It's probably instigated at least as
> much by something that's fsyncing every ~90 seconds like the journal
> or rsyslog.

At that rate, in about 5 days smartd will start reporting "FAILING NOW"
for that attribute.  The performance impact of having to wait for the
heads to reload every 90 seconds should be noticeable.  The only
advantage of _not_ having the heads flying over the platter surface is
about 1 Watt decrease in idle power.  Seagate specs the idle power at
4W, with a note "5W with DIPLM enabled" (whatever "DIPLM" is -- I can
find no information on that, or how to enable it).

-- 
Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.



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