Disk Utility: Trouble Formatting or Erasing that Windows PC Hard Drive?

June 22, 2009 in Tips & Tricks by Mark

So you are trying to format a drive you know is setup for PC or Windows. You keep getting an error stating Disk Erase failed, or /dev/rdisk1s1: partition size not a multiple of 4K. Its not so much an error, but rather a common oversight.

Step 1: The Problem

So there you are, with your spare or new internal/external hard drive. You know its formatted for a PC with NTFS or FAT32. So you plug it in and try to Erase it with Disk Utility App with the filesystem Mac OS Extended (Journaled). Only to get a pesky error stating:

Disk Erase failed with error: File system format failed.
/dev/rdisk1s1: partition size not a multiple of 4K.

The problem is you are trying to put an incompatible filesystem on the Master Book Record Partition Map Scheme.


Step 2: Solution: Partition Area

Select the Partition tab. Then select Volume Scheme: and set the desired number of partitions you would like to use.


Step 3: Partition Options + GUID Partition Table

The previous step will bring up the Partition Options. Select GUID Partition Table and click OK.


Step 4: Done!

Now back on the Disk Utility Partition screen notice the Format section now says Mac OS Extended (Journaled).

Click Apply and the Partition Disk Waring will appear. Click Partition. **This will erase all data.

That’s it, it will create the partition with GUID options and format the drive in the correct filesystem.


Disk Utility, Hard Drive, PC to Mac