On my Macintosh computer, why can't I format or partition the internal hard drive?

If you are unable to format or partition the internal hard drive on your Mac OS or Mac OS X computer, your hardware may have suffered physical damage and may no longer be functional. Consult your local retailer or repair shop for advice.

However, in Mac OS more commonly the source of the problem is software-related. See In Mac OS X, why can't I unmount my drive to initialize it? Also, take the following into consideration:

• If you are trying to use the Internal HD Format or HDSC Setup utilities, consider using Drive Setup instead. Internal HD Format and HDSC Setup should be used only with older computers and won't work at all on many systems.
  
  
• If you are trying to initialize or partition a disk that you bought from a third-party vendor, use the formatting utility that came with it, rather than the ones Apple provides.

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