Re: Disk heads won't park [pat II]
On 4/29/2014 1:20 PM, Nuno Magalhães wrote:
> Reviving this thread since i tried turning the machine on again (and
> amybe another thread will bump this one).
>
> And, again (well i wasn't expecting it to go away), as soon as the
> machine starts - right after POST, even before GRUB - the drive starts
> making "reading noise" (like when an antivirus is scanning or the
> system is thrashing). The only way it stops is with hdparm -y (no
> wonders there).
The drive isn't failing, but has failed. Replace it.
Mechanical drive platters have hard coded track markers. These are
created by a "low level format" at the factory on today's drives. Those
with experience going back to MFM/RLL days may recall performing low
level formats due to stepper motor issues. This was done by entering
"g=c800:5" in a debugger, which loaded and executed the controller's
firmware format utility.
Drive firmware reads the low level track markers in order to properly
position the read/write head on user data tracks. The noise you are
hearing is the head seeking across the platter trying to locate the
track markers and it is unsuccessful.
The likely cause is a worn out actuator return spring. This is a rather
common failure mode. The cost of the return spring is about USD 0.0025,
about a quarter of a cent. If the spring tension deviates too far from
spec the head will no longer align to a track marker. While Q.C. is
typically good on spring manufacturing, they are made from large spools
of drawn steel wire. A slight imperfection in a few feet of a 10,000
foot spool will yield a few dozen springs that may not last long, in
your case about 2.1 years.
Worn out spindle bearings can also cause head locating problems, but in
this case you'll usually notice a vibration in the PC case and likely a
hum accompanying it. Q.C. on the bearing assemblies is much higher than
return springs. The spindle assy is the most expensive part in a disk
drive due to the manufacturing tolerance and spin balancing required.
You usually don't see bearing wear issues until 5+ years of power on
duty. And of course bearing wear is inversely proportional to spindle
speed. I.e. 5K drive bearings should normally last longer than 15K
drive bearings.
No software tool can identify the cause of your problem. However, SMART
has been telling you for some time that the drive was experiencing seek
errors. Seek errors indicate a head positioning problem. A head
positioning problem normally indicates a worn return spring, bearings,
or possibly a problem with the voice coil or its drive circuit, though
the latter is rare.
Cheers,
Stan
> This is a Seagate Barracuda ST31000528AS drive with a CC49 firmware
> upgrade. Here's a few other commands i tried:
...
> 7 Seek_Error_Rate POSR-- 075 060 030 - 35143152
...
> I do assume it is failing, but i'd like to know why and which values
> are really tell-tale (for instance the WHEN_FAILED column above is
> empty, so i can't realyl draw any conclusions).
>
> This is a recently installed, headless system with almost nothing installed.
>
> Thanks,
> Nuno
>
>
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