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After formatting an external hard drive with OS X's diskutil, the disk is automatically split into 2 partitions like so:

Finished partitioning on disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk1
   1:                        EFI                         209.7 MB   disk1s1
   2:                  Apple_HFS Milosz Pass             499.7 GB   disk1s2

Now, since this is my external HDD that's not using for firmware upgrades/booting or whatever the EFI partition might be used for, I assume I might as well delete it and use the extra 200MB for something else. But how do I do that?

Using diskutil partitionDisk and explicitly stating that I only want 1 partition to be created, it still creates the EFI partition alongside the other one. Any hints I was able to find so far described how to do this under Windows, but surely there must be a way to do this on OS X as well.


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up vote 1 down vote accepted

I must yet find out what difference it makes, but* choosing MBR as the partition map scheme gives the desired result.

Hence, running diskutil partitionDisk /dev/disk1 1 MBRFormat HFS+ "Milosz Pass" 500G on the same disk as above, results in the following partition layout:

   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *500.1 GB   disk1
   1:                  Apple_HFS Milosz Pass             500.1 GB   disk1s1

Notice the ~400 MB space increase.

*Read up on the differences between the default GPT scheme and the MBR here. Also have a look at common myths pertaining to partition map schemes, EFI and more here.

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