MacOS – My whole HD is “Mac OS X Base System”

boothddmacos

my entire HD is now "Mac OS X Base System":

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ps: Mac OS X Base System is Disk0s2

I cant delete this partition to install Mac OS X; I already try the terminal, but message reply "you cannot erase the boot disk".

Does anyone have any idea how can I fix this?

Best Answer

Probably your pMBR/GPT got corrupted or the Base System is somehow mapped falsely. Usually the first partition (EFI) and the last partition (Recovery HD) aren't visible. Additionally a freshly erased disk0s2 ususally contains ~200 MB and not 1.4 GB (which is "by accident" the uncompressed size of a Base System).

The best thing is to completly erase the internal disk by whether:

  1. Booting to Internet Recovery Mode by hitting altcmdR immediately after the start chime, repartitionung the internal HDD to one partition and installing a new system.

or

  1. Attaching a thumb drive and installing a fresh system there. After rebooting from the thumb drive, repartition the internal HDD and install a fresh system to the internal disk.

In both cases the invisible EFI partition will be build automatically as well as the Recovery HD while installing a new system.

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