I have a Mac Pro running Mac OS X Lion, and one of my hard drives has acted weird since attempting to repair permissions. I used Disk Warrior, but it says the HD can't be rebuilt. When I try to format it with Disk Utility, it takes forever to unmount.
I'm wondering if there is a surefire way to format the HD with another program or through the command line.

The HD is 2TB, and the SMART status is verified, so I doubt it is a physical issue.

  • 2
    I would not rely on a "verification" by S.M.A.R.T. status as a good indicator of whether the drive is free of physical problems. "Work at Google on over 100,000 drives has shown little predictive value of S.M.A.R.T. status as a whole ..." Source: en.wikipedia.org/wiki/S.M.A.R.T. Did you run a hardware scan in Disk Warrior? What additional information does it report when trying to repair the partition? An inability to repair the filesystem is not generally a good sign. If possible, I would RMA the drive. You truly have no way of knowing if this graver things to come.
    – user10355
    Commented Dec 18, 2011 at 0:28

2 Answers 2


Many problems can cause such a problem. SMART status is unreliable, but it's good that it's at least 'OK'.

If you don't care about data and just want to format and repartition your HDD then you can:

  1. Check the disk for bad sectors. If it contains bad sectors it may be not a good idea to use such a disk at all. Here are some nice tools that can be used for this.

  2. wipe the disk using dd (make sure that you wiping right drive):

    dd if=/dev/zero of=[path to device] bs=1M

  3. Partition it using Disk Utility


One thing I always do if I can is run a program called SpinRite (https://www.grc.com/sr/spinrite.htm), though you will need to remove it and put it into a PC. It does a very low level scan for sector errors. You can learn more about it on that website.

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