Removing boot information from drive?

Discussion in 'MacBook Pro' started by skiltrip, Mar 5, 2011.

  1. skiltrip macrumors 68030

    Joined:
    May 6, 2010
    Location:
    New York
    #1
    Not sure what happened this morning, but I'll try to explain.

    I have an external 1TB OWC firewire drive for audio.

    I also have aUSB bootable clone from my old 13" MBP. I want to reuse this drive to clone my new MBP, but I wanted to back up all the files first just in case.

    So temporarily, I was going to just select ALL, and copy the entire drive to a folder on my 1TB audio drive. Just so I'd have the stuff. Just used Finder to do the copy. But a few minutes in to it. Maybe it was 15 minutes. I'm not sure. I canceled it. I didn't want to commit to copying it over just yet. I had some work to do. So I then deleted the temporary folder I had on my audio drive.

    Now here's where the problem starts...

    I have on my firewire, first my M-Audio ProFire audio interface, then the OWC 1TB drive chained to that. It's been working great since I got this new MBP on Wed. No problems.

    After I tried that copy, now 9 out of 10 times, I can't boot properly if the OWC is on while I'm booting. What I get is a long boot time, followed by a washed out looking desktop. A mouse pointer is there, but I can't actually click on anything. If I shut off the OWC drive it unmounts, and the desktop goes to normal.

    If I boot with the OWC turned off, it boots fine. And when I turn it on after I'm booted, it mounts normally. But I can't boot with it already powered on.

    Could I have copied some boot record files over or something to the OWC drive, and the MBP is getting messed up booting because it doesn't know where to boot from? And if so, can I check to see if there is boot info on there, and is there a way to delete it? When I go into Disk Utility, and click Info for the OWC drive, it say "Bootable: YES".
     
  2. Voondebah macrumors member

    Joined:
    Mar 28, 2010
    #2
    It really should not have been possible to copy boot code information. Under the GUID partition scheme, all partition information is descibed at the beginning of the drive in the partition map. There are entries for each partition in this map, and there's a part of this entry that describes whether the partition is bootable or not. It really should not have changed from just copying files through finder, so I doubt your problem has anything to do with boot code.

    Even if it somehow happened, it wouldn't be easy to change the bytes that describes the partition as bootable or not. GPT contains a checksum, so if you change any info in the partition map, you'll have to know what to change the checksum too, or else the partition map will appear invalid.
     
  3. skiltrip thread starter macrumors 68030

    Joined:
    May 6, 2010
    Location:
    New York
    #3
    Why does it say the drive is bootable under disk utility though? Does it say this about any drive?
     
  4. Voondebah macrumors member

    Joined:
    Mar 28, 2010
    #4
    This seems like quite a weird problem! If your have your Restore discs or a OS install disk, I would try booting to these. Insert the disc, restarc computer and hold 'C' on the keyboard til it boots to the disc. It should be possible to access Disk Utility from one of the menus at the top after you get past the language select screen. Try and use the disk utility to Repair your drive - this option should be accessible from the first aid tab. You could run Repair as well as Repair Disk Permissions.

    Hopefully booting to the disc will allow you to have the drive connected without locking up the whole system.
     
  5. skiltrip thread starter macrumors 68030

    Joined:
    May 6, 2010
    Location:
    New York
    #5
    Thanks. I think later I'll copy all my audio files onto another drive (I already have one backup, but I'll make a 2nd) before I start messing with it. Then worst comes to worse, I'll just wipe it clean and then copy my audio files back on to it.
     

Share This Page