Motion Sensor

[tjb1]

I know the MBP has the motion sensor, im pretty sure this is built into the computer correct? and I know the stock hard drive had the option(cant quite remember but it had something to do with the motion) Does that option mean the HDD has the capability to stop due to motion using the MBP motion sensor or does the HDD have its own sensor?

 

[spinnerlys]

The It's the Sudden Motion Sensor is built into the notebook and not the HDD. It senses sudden motion and gives the HDD read/write head to stop immediately any ongoing process and removes it from the platter to prevent any scratching.
The It's the Sudden Motion Sensor is not built into the HDD, though some HDDs come with so-called AntiShock systems.

 

[ArmCortexA8]

I know the MBP has the motion sensor, im pretty sure this is built into the computer correct? and I know the stock hard drive had the option(cant quite remember but it had something to do with the motion) Does that option mean the HDD has the capability to stop due to motion using the MBP motion sensor or does the HDD have its own sensor?

The actual sensor is built into the hard disk itself and it detects rapid movement and you will hear a "ping" sound. Simple test put your MacBook on a soft bed wait a couple of minutes and put one finger on the left and one finger on the right and push quickly down with both fingers at the same time - you will heard the sound. The sound is created by the Sudden Motion Sensor - apparently Hitachi are louder than some. This is normal functionality, nothing to be worried about.

 

[tjb1]

So does that mean every HDD is capable of stopping safely with the computer command? Reason im asking is I have the Momentus XT now and I am almost positve when I looked up the model number of the 500gb 7200 it said something about motion sensor and if the Momentus XT isnt capable of this, im going to disable it using the terminal command provided by apple.

 

[spinnerlys]

So does that mean every HDD is capable of stopping safely with the computer command? Reason im asking is I have the Momentus XT now and I am almost positve when I looked up the model number of the 500gb 7200 it said something about motion sensor and if the Momentus XT isnt capable of this, im going to disable it using the terminal command provided by apple.

Yes, since Apple introduced the SMS in 2005 for its PowerBook and iBook line, every HDD will work, except the ones with a built-in AntiShock system, which can be disabled though via some hack.

@ ArmCortexA8: As far as I have heard and read, the SMS is built into the logic board and transmits the signal to stop the HDD write/read head to the HDD itself. There is no motion sensor in many HDDs anyway.

 

[GGJstudios]

The actual sensor is built into the hard disk itself and it detects rapid movement

No, SMS is built into the notebook, not the hard drive:

The Sudden Motion Sensor (SMS) is Apple's patent-pending motion-based hardware and data-protection system used in their notebook computer systems.

So does that mean every HDD is capable of stopping safely with the computer command?

Yes. SMS is drive independent, so it will work with any drive you install.

I have the Momentus XT now and I am almost positve when I looked up the model number of the 500gb 7200 it said something about motion sensor and if the Momentus XT isnt capable of this, im going to disable it using the terminal command provided by apple.

Among the MacBook and MacBook Pro community there have been several owners who installed aftermarket hard drives already equipped with anti-shock features who reported experiencing Kernel Panic errors whenever their unit was physically moved. This is believed to be due to a conflict between SMS and the new drive's anti-shock function. The Western Digital Scorpio series of notebook hard drives have been the most frequently reported as being susceptible to this problem. In practically all cases, disabling SMS alleviated this problem without any negative performance impact.

 

[ljx718]

some ppl that complain that the laptop makes noice when you move it dont know that its the sensor going into effect and parking the hdd

 

[ArmCortexA8]

Yes, since Apple introduced the SMS in 2005 for its PowerBook and iBook line, every HDD will work, except the ones with a built-in AntiShock system, which can be disabled though via some hack.

@ ArmCortexA8: As far as I have heard and read, the SMS is built into the logic board and transmits the signal to stop the HDD write/read head to the HDD itself. There is no motion sensor in many HDDs anyway.

Thanks for the update, I'm only very new to Mac - two weeks max, so now I know the sensor is on the board not the drive. Interesting.