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MBP Freezes When Lightly Repositioned: TEST YOURS

S

Sherman90

macrumors newbie
Original poster
Jan 7, 2009
27
0
I'm wondering if this is unique to system.

Here is the test:

1. Load up any movie that is ripped to your hard drive - i.e. DIVX etc.
2. While playing, lift the laptop in the air a few inches and let it drop gently to your lap. You can also try to firmly "tap" the bottom/front/right of the MBP (where the hard drive is) for the same result.

Does the movie freeze? Stutter? Mine does.

I'm led to believe that either my particular HD is overtly-sensitive, improperly installed or defective, or else that the HD is generally too exposed in the Unibody design. I wouldn't find this problematic except that movies freeze and stutter with often the slightest movement while the notebook is on my lap.

Please post your results.
 
Why would you even drop your laptop, even if it's gently.

The reason it skips is cause the movie file is constantly accessing data from the source in order to keep showing the picture, so if you bump the harddrive of course it's gonna skip.
 
mikes70mustang said:
wow, seriously. this should be named, "hey i try to ruin my hard drive u should too.
Click to expand...

It's a legitimate question. Especially if you use your computer in the car, or have a severe case of parkinsons :D

I don't have a unibody MacBook to test, but my SR MacBook doesn't do what you described with an mp4 file from iTunes.
 
I've owned 4 laptops prior to this MBP and never experienced this before, so I'm prone to think it's not me: it's either the design or the hard drive.

Just to clarify: I am talking about lifting the laptop up and placing it back down on your lap without the neurotic fears of a converted hardcore materialist.

I'm handling a notebook not a newborn baby with an iron deficiency.
 
It's the sudden motion sensor locking the hdd so the head doesn't collide with the platters. That's what it's supposed to do
 
Does it happen on yours PJ? Did you test it?

That's what I thought might be happening: I would still consider it a design flaw if it's so overtly sensitive (as mine is).
 
Sherman90 said:
Does it happen on yours PJ? Did you test it?

That's what I thought might be happening: I would still consider it a design flaw if it's so overtly sensitive (as mine is).
Click to expand...

It's normal. It happened to me and I have a Alu. MacBook with a 5400RPM Seagate Harddrive.
 
Sherman90 said:
Does it happen on yours PJ? Did you test it?

That's what I thought might be happening: I would still consider it a design flaw if it's so overtly sensitive (as mine is).
Click to expand...

Yeah I can hear the click when I shift mine sometimes. Why shouldn't it? If there's a chance that the hdd could get damaged, I'd rather it be super sensitive than make sure my divx videos play back without interruption. Besides, when my computer is moved enough to trigger the sensor, usually I'm focused on something other than what's on the screen, so what do I care if it freezes for a second?
 
design flaw or not, you dont typically juggle your laptop while your watching a movie do you?
 
this same thing happens to me in a penryn mbp its just the hard drive sensor telling it that its falling and stops itself
 
The above poster is correct on the HD sensor, however this drive should be reading ahead and buffering at least ten seconds to allow the HD to recover. This read ahead technology is in EVERYTHING, including ipods from as far back as the beginning. I remember them mentioning it as an actual feature in the earlier HD ipods. It was their skip protection.
 
That is most likely the sudden motion sensor that grabs your HDD's actuator arm so that the disk doesn't get gouged. This is what causes the stutter in data read. If you want to turn it off this would solve the problem - if you consider it to be a problem - but if you drop it too fast or tap it too hard you will hurt your disk.

open up a terminal window
type: sudo pmset -g
in the second line, across from the sms (sudden motion sensor) you'll see a 1, this means that it's on.
now type: sudo pmset -a sms 0
type the first command again to see if it's worked, the 1 across from the sms should now be a 0. Now that the sms is off your data read won't study, but as I mentioned early you could hurt your drive since the sudden motion sensor exists to protect the drive.

To turn the sms back on run the same command but replace the 0 with a 1. sudo pmset -a sms 1
You can check to see if it's on or off by using the sudo pmset -g


ps. also only do this if you're running 10.4 or 10.5, the commands for earlier os x releases is a little different I think
 
As others have stated, your sudden motion sensor is probably tripping and locking the drive mechanism for safety reasons.

That said, I think for the sake of the scientific method the OP should post the specs of the machine in question, so people with *similar* machines can see if theirs suffer the same symptoms. A systematic and structured approach is beneficial to determining the exact cause.
 
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