2011 MBP comes with G-Force drive as stock?

Discussion in 'MacBook Pro' started by SiriusExcelsior, Jun 20, 2011.

  1. SiriusExcelsior macrumors regular

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    #1
    Hey guys,

    I recently got a 15" Sandy Bridge MBP (2.0 GHz), and had been researching on getting a second HDD/SSD (via OptiBay) when I realised something.

    My MBP came with a 500GB Seagate ST9500325ASG (5400.6) as stock. The G at the end of the model number seems to indicate that it's a G-Force-equipped drive, according to Seagate's website.

    Question 1: I thought there were incompatibilities with SMS and an HDD's own shock-sensor? Have these been solved?

    Question 2: I can't find the place where it says if the SMS feature is supported/enabled; I remember it being in System Profiler>Serial-ATA, but not any more. Using Terminal to check (with pmset) yields an "sms 1" though. Does this mean SMS still exists? Or does it now report if an HDD supports some kind of movement sensing on its own?

    Question 3: Would SMS stop a drive installed on the optical drive SATA connector?

    Thanks!
     
  2. bozz2006 macrumors 68030

    bozz2006

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    #2
    1. There were. I don't know if there still are. Most of Apple's stock HDDs now come with built in SMS, though, and Apple computers still have the SMS on by default

    2. Yes, it still exists, and sms 1 indicates that it is on and active. Terminal reports back on the computer's built in SMS.

    3. No.
     
  3. Erasmus macrumors 68030

    Erasmus

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    #3
    If you're going to put your hard disk in the optical drive (where SMS won't work) and rely on the HDD's inbuilt system, you can verify it's working after the conversion by playing music, and (reasonably gently) shaking the computer. If the G-Force system is working, the music should skip.

    As the G-Force system should lock the HD if it's in free-fall, you should tailor your shaking ferocity appropriately. ie, tossing it a few cm in the air, and catching it.
     
  4. bozz2006 macrumors 68030

    bozz2006

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    #4

    itunes caches music so it won't skip. I think you have the macbook confused with...
    [​IMG]

    I don't mean to come off as rude here, buuuuuuuut your suggestion just doesn't strike me as a good idea.
     
  5. Erasmus macrumors 68030

    Erasmus

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    #5
    I decided to walk to Uni one day with music playing through headphones from iTunes on my computer, which was in my backpack. The music skipped. A lot.
     
  6. bozz2006, Jun 20, 2011
    Last edited: Jun 20, 2011

    bozz2006 macrumors 68030

    bozz2006

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    #6
    Yep, and how long did it take to start skipping? I'll admit that I overstated things a bit. It has a cache so if you're playing a song and shake it for a few seconds, it won't skip. Same idea as the skip protection on the later portable CD players.

    I suppose if you start one song then shake it as you're selecting a different song from a different artist or something, it might skip.

    But, I mean, that's not really a way to tell if your hard drive has built in SMS. It'll eventually skip regardless of whether it has built in SMS or not. Easier to check system profiler for manufacturer and model, then check out their website.
     
  7. KJmoon117, Jun 20, 2011
    Last edited: Jun 20, 2011

    KJmoon117 macrumors 6502a

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    #7
  8. Erasmus, Jun 21, 2011
    Last edited: Jun 21, 2011

    Erasmus macrumors 68030

    Erasmus

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    #8
    It didn't take all that long to start skipping. A few seconds I think.
    And I don't think it would start skipping if it doesn't have SMS, as the HDD wouldn't ever be parking the needle in preparation for a hard landing. I expect it would take a much larger shock (than +/- 1G) to cause the needle to shift sufficiently to start causing read errors without SMS enabled.

    EDIT: I just tried playing a Full HD movie off the hard disk. With what can only be described as gentle waving in the air, the movie instantly stops. Playing a standard definition movie, and doing the same thing, it plays smoothly. (Both m4v files encoded with Handbrake)

    So download Big Buck Bunny (if you don't have a Full HD movie on hand) and give it a shot.
     
  9. SiriusExcelsior thread starter macrumors regular

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    #9
    That's what I'm not sure of.. SMS could well be identifying HDDs shipped by Apple (via custom firmware or whatnot) and only sending commands to those, or it could send commands only to the HDD bay, and not the ODD bay. Given how Apple's connected the ODD to a SATA II port rather than a SATA III for no good reason, I wouldn't put it beyond them to selectively send SMS commands. But that thread gives some hope :)

    The specs for my particular HDD shows that it supports G-Force, but could be deactivated via Set Feature commands. Which means I still have no idea if it's SMS or G-Force that's directing my HDD right now.. haha.

    I agree with bozz. I've always wondered if the bearings that clamp HDD platters to its axle were strong enough to overcome the gyroscope effect when you change the HDD's orientation while it's spinning. It only needs to shift a few microns up or down for a head crash to occur, IIRC. I highly doubt that that's what's happening in your case, since it wouldn't resume playing if it had a head crash, but I wouldn't want to try that myself, either :D


    I've also tried some programs that utilise the tilt sensor/accelerometer used for SMS (LiquidMac, SMSRotateD, StableWindow), so I've independently confirmed that the sensor still exists, at least, meaning that SMS is still available.

    I've also found the SMS status entry in the System Profiler.. it was under the Hardware Overview page.. "orz
     
  10. Erasmus macrumors 68030

    Erasmus

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    #10
    I doubt whether modern hard disk platters are very heavy, and hence do not have a high gyroscopic moment. Furthermore, as the read head is so light, and is supported by air movements on the surface of the platters, the drive head will follow the platter, not the drive case, should any internal twisting occur.

    Considering the acceleration caused by gently waving your computer around would be like less than half a G, the only chance of damage occurring to your hard disk is if SMS is not enabled, and you accidentally drop your computer while waving it around.

    To me, your arguments seem like saying throwing peas at people is dangerous, considering shooting bullets at people is.
     
  11. SiriusExcelsior thread starter macrumors regular

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    #11
    True that; I forgot that the head is supported by air currents. I was quite surprised when I first learnt that.

    I'm pretty sure that at least one person has been killed as a result of someone throwing peas :cool:
     

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