[TriLUG] Hard drive recovery

[Joseph Mack NA3T via TriLUG]

On Sat, 13 Apr 2019, Brian Henning via TriLUG wrote:

> The rotation-axis flick after applying power has helped me get a fussy drive 
> spinning.

I've not heard of that. I only know poking the platter after popping the lid.

> Shay says "rotate the drive".  It's an action a bit more vigorous 
> than the word implies; a "flick of the wrist" might give a better suggestion 
> of the actual move involved (you want to impart some rotational momentum to 
> help the drive get turning).

good to know.

> I also agree with the folks who say don't try the freezer trick, for a couple 
> reasons:

> 1. Stiction - This happens when the lubricant sealed inside the drive motor 
> becomes thick with age, resulting in too much friction at startup.  Cold makes 
> this worse, as most lubricants thicken at lower temperatures.

I've never had a problem running a disk in a freezer. If it starts up at room 
temperature, it starts in the freezer too.

Since we're talking about lubricants ... There was a change in spindle 
lubricants a little while ago (not sure when, but sometime around when disks 
changed from IDE to SATA).

The old style lubricant (IDE) went solid with age. If you sat a disk on a shelf 
for a while (a year or two) it would not spin up. I pull my disks after about 
two years and park them on a shelf. If I needed a disk for a non-critical job, 
I'd take one off the shelf. Often they would not spin up. I assumed this was 
just what happened as disks age, but it turns out it's the lubricant. I could 
have kept the disks working, by just running them for a couple of hours every 6 
mo. The new lubricant (SATA drives) will not seize with age.

The info about this is on various webpages. I looked it all up when I found out 
about the change in lubricants, but I've forgotten the details.

> 2. Condensation - Drive enclosures are not sealed from the atmosphere; in 
> fact, they have breather holes that must never be covered.  Breather holes by 
> which humid air can reach an icy-cold platter and condense.

you can keep things dry. Gary, in a previous posting, described the way to do 
it.

When I was new to this proceedure, one drive wouldn't start, and it was because 
the circuit board was wet (I had brought it out of the freezer, bare metal, into 
my room. it must have been summer). I let it warm up and dry off and I tried 
again inside a zip lock bag with paper towels and it was fine.

I've never had anything attributable to condensation inside the disk. Maybe I've 
only done this in winter when the dew point is well below freezing. Maybe any 
condensation has been flung to the outside walls of the spinning disk holder.

> If the drive is not mounted in an enclosure, it's easy to tell if it's 
> spinning or not by testing for gyroscopic precession.  Power up the drive, 
> hold it flat, and very gently rock it side to side.  If the drive is spinning, 
> you'll feel a slight force at a right angle to the rocking motion (the drive 
> will feel like it's trying to twist in your hand).  A non-rotating drive will 
> not have this effect.  This test is useful if you're not sure you can hear the 
> motor or not.

I've always been leary of rocking a spinning disk. I don't like moving a working 
disk. I worry that the platters will gyroscopically tilt and crash into the 
head(s). I have no idea how much leeway you have to do this. You say gentle. If 
you say it's OK, I guess it is.

I saw a technician unplug a disk running on a bench and, while it was spinning 
down, held it in his hand, twisting it every which way, to show the strong 
gyroscopic effect. I guess the disk was safe; as soon as the power dropped, the 
heads are pulled back to park by a spring. Still I was alarmed. It wasn't my 
disk so I just watched.

Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant
map generator at http://www.wm7d.net/azproj.shtml
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