To avoid data loss, you must back up your Mac or the external storage device before performing the erase operation. So, you lose access to all your files from the drive. The Erase operation replaces the old file system of the storage drive with a new one. Master Boot Record: Prefer this scheme for compatibility with Windows-based PC.Īpple Partition Map: Use this scheme for compatibility with old PowerPC-based Mac. Even, some latest Windows PCs use this scheme.

GUID Partition Map: Select this scheme for all Macs that are based on Intel and Apple Silicon. Disk Utility provides the following three schemes: You need to enter a few details such as name, format, and scheme before you erase the storage medium. The Erase feature of Disk Utility allows you to format your Mac hard drive with a new file system. I really have no clue what could be the problem.Disk Utility is a native macOS application that offers multiple storage disk management features, such as First Aid, Partition, Erase, Restore, Unmount, and Info. The mac book model is A1278, and I'm using a samsung ssd.

I also tried to rebuild the partition table using 'fdisk' and 'gpt' or unmounting using 'diskutil unmountDisk' with no success. If I try to boot internally with the original HD, it works fine.

The ssd works fine in the original mac book if I try to install it from a usb adapter, so I tried to install the fresh OS using the usb adapter, and everything worked fine, but when i try start the system with the ssd internally, I receive the prohibitory symbol. I tried to install again after formatting the ssd in different computers and formats (NTFS, mac os extended, exFAT, FAT) and writing over the ssd with zeros but got the same problem. I can format and use the ssd normally anywhere else (in windows or another mac as an external ssd). The repair lasted 5 seconds but it failed and it would not let me repair anymore. The back story is that the mac book was not coming back on from the sleep, so I had to force shutdown a couple of times, I believe the update failed and messed something, and eventually I was unable to turn it on, so I used disk utility to try to repair the drive. In the recovery mode I try to install High Sierra from a usb with the ISO or even from the internet recovery and receive an error that says permission denied or when I try to format using disk utility it says the erase/format failed, can't unmount disk. When I start my mac book pro (mid 2012, non-retina) it takes a long time to appear anything (1min) and it shows a p rohibitory symbol instead of the apple logo.

I searched a lot for this but could not find the answer anywhere.

Mac os disk utility format