intermittent S.M.A.R.T. errors: corrupt S.M.A.R.T. info

[crowbar]

I've occasionally been getting "S.M.A.R.T. Status Bad: Backup Drive
and Replace" error messages for a 100GB Western Digital drive
on-and-off since I re-connected it last night after unsuccessfully
troubleshooting a WIndows installation.

I fear the magnetic end of a dual-ended screwdriver may have
accidentally got too close to the drive (it was working error-free
before, even after the Windows crash). No errors are reported when
scanning the surface of the drive with Windows Disk Management, CHKDSK
or the Western Digital diagnostic utility but the error would
reappear, often at the next reboot (only to then disappear again after
a few more reboots).

I checked the S.M.A.R.T. Disk information and nothing seems too
alarming, except for the UltraDMA CRC Error Rate: the current value is
200, the threshold is 0 and the worst value is 253. How can the worst
value be higher then the current value?! Would this indicate a problem
with S.M.A.R.T. Disk Information that could be triggering a false
error message? Thanks for any wisdom, it is much appreciated

 

[Arno Wagner]

I've occasionally been getting "S.M.A.R.T. Status Bad: Backup Drive
and Replace" error messages for a 100GB Western Digital drive
on-and-off since I re-connected it last night after unsuccessfully
troubleshooting a WIndows installation.

Usuelly you should take a SMART warning literally.

I fear the magnetic end of a dual-ended screwdriver may have
accidentally got too close to the drive (it was working error-free
before, even after the Windows crash).

Was it spinning at that time? Non-spinning disks are pretty immune to
normal magnets. Spinning ones arent, if their platters are conductive.

No errors are reported when
scanning the surface of the drive with Windows Disk Management, CHKDSK
or the Western Digital diagnostic utility but the error would
reappear, often at the next reboot (only to then disappear again after
a few more reboots).

I checked the S.M.A.R.T. Disk information and nothing seems too
alarming, except for the UltraDMA CRC Error Rate: the current value is
200, the threshold is 0 and the worst value is 253. How can the worst
value be higher then the current value?!

This does not sound right. Maybe your SMART-tool is broken?

Would this indicate a problem
with S.M.A.R.T. Disk Information that could be triggering a false
error message? Thanks for any wisdom, it is much appreciated

Maybe. Still, you should back up any important stupp on that disk.

Arno

 

[skinnypuppy]

Was it spinning at that time?

The disk was off; I was just attaching the mounting rails to the HDD at
the time the magnetic end grazed the belly of the drive. I didn't want
to be using that particular screwdriver since I knew eventually I was
bound to accidentally use the magnetic end but it was the only
screwdriver slender enough to fit through the slots in the railing. I
didn't even know for sure that the magnetic end posed a real threat but
I wanted to be cautious, especially after all the other storage
problems I've been experiencing as of late.

http://img3.exs.cx/img3/197/DSCN3827.jpg
http://img11.exs.cx/img11/1037/DSCN3831.jpg

This does not sound right. Maybe your SMART-tool is broken?

I tried another S.M.A.R.T. info utility (AIDA32) and got the same info.
Actually, AIDA additionally showed me the raw data of 216, while this
value is set to 0 on my newest drive. Don't know how to interpret it
but I'm still hoping its just a fluke in the S.M.A.R.T. subsystem and
not a real problem (worst value should still be less than current
afterall).

http://img25.exs.cx/img25/5274/aida32.jpg

 

[Folkert Rienstra]

Usuelly you should take a SMART warning literally.

And alcohol destroys the brain.
'Usuelly' you should take that warning literally.

Was it spinning at that time? Non-spinning disks are pretty immune to
normal magnets. Spinning ones arent, if their platters are conductive.

Obviously braindead.
Besides, he is getting Interface CRC errors after he 're-connected' it.

 

[Joep]

Don't know how to interpret it
but I'm still hoping its just a fluke in the S.M.A.R.T. subsystem and
not a real problem (worst value should still be less than current
afterall).

You better read up on SMART before 'using' it because your missing some
things. SMART typically counts *down* towards a threshold.

 

[Folkert Rienstra]

Actually, current can also *be* the worst, so that would be less_or_equal.

You better read up on SMART before 'using' it because your missing some
things.

Are you sure that *you* aren't missing something?

SMART typically counts *down* towards a threshold.

Yes, and?

 

[Arno Wagner]

And alcohol destroys the brain.
'Usuelly' you should take that warning literally.

Obviously braindead.

No, with a clue in physics. Unlike certain other people.

Arno

 

[Alexander Grigoriev]

The magnetic coating is not that easily demagnetized. I doubt a regular
ferrite magnet (from a speaker) will affect it even if applied directly. I
used to be able to erase 360 kB floppies with such magnets. 1.2M floppies
already were not prone to that kind of magnet.
Hard disks coating is much more difficult to erase.

 

[Joep]

Are you sure that *you* aren't missing something?

Well, I am a happy camper basically. Possibly I overlooked something yes if
that's what you mean.

Yes, and?

Brilliant reply. So productive.

 

[Arno Wagner]

The magnetic coating is not that easily demagnetized. I doubt a regular
ferrite magnet (from a speaker) will affect it even if applied directly. I
used to be able to erase 360 kB floppies with such magnets. 1.2M floppies
already were not prone to that kind of magnet.
Hard disks coating is much more difficult to erase.

Indeed. However if a conductive platter is spinning in a magnetic
field, there will be locally induced currents. They in turn can erase
a disk within some time. There was a number of incidents of this type
with notebook HDDs in german trains some years ago. The trains were
this happened had newly introduced fold-down tables with strong
magnets at the corners.

Notebook HDDs have less distance between their case surface
and the platters. And it might have taken up to an hour or more
with a disk spinning most of the time for the damage to happen.

Arno

 

[Joep]

I checked the S.M.A.R.T. Disk information and nothing seems too
alarming, except for the UltraDMA CRC Error Rate: the current value is
200, the threshold is 0 and the worst value is 253. How can the worst
value be higher then the current value?!

I found this ...

Western Digital firmware initializes SMART Attributes 10, 11, and 199 after
either 120 spin-ups or 8 power-on hours. Until that time, they have the
uninitialized value 253.

 

[Folkert Rienstra]

No, with a clue in physics.

Obviously not.

Unlike certain other people.

Right, and that is why you made that CRC error stuff disappear,
because 'you have a clue in physics, unlike certain other people'.

 

[Folkert Rienstra]

Indeed. However if a conductive platter is spinning in a magnetic
field, there will be locally induced currents.

They in turn can erase a disk within some time.

A direct stray magnetic field, not strong enough to erase bits by
itself, will induce a huge current in the platter so that its magnetic
field will erase the bits. Yup, you know your physics alright, Arnie.

There was a number of incidents of this type
with notebook HDDs in german trains some years ago.

Have we forgotten that Notebook HDs have glass substrate platters?