Create CentOS bootable USB installer on Mac OSX

Create a bootable USB drive with the CentOS 7 installer ISO file on Mac OSX (Apple MacBook).

Steps:

1. Format a USB drive as eFAT with Disk Utility
2. Download CentOS 7 Full or Minimal iso file
3. Open terminal and find USB drive partition name with command “diskutil list“
4. In the terminal, use the dd command to copy CentOS iso to USB
5. Test USB drive in Parallels virtual machine

FIND USB DRIVE PARTITION

In terminal, run command “diskutil list” to view partitions, the usb drive will be the last one listed.

Screenshot of the USB partition /dev/disk2 formatted as eFAT (but shows Windows NTFS)

Unmount Disk

diskutil unmountDisk /dev/disk2

COPY CENTOS 7 ISO TO USB DRIVE WITH DD

Run the following command to copy iso drive to the usb drive, this command makes the usb drive bootable.

sudo dd if=./Downloads/CentOS-7-x86_64-DVD-1611.iso of=/dev/rdisk2 bs=1m

Note the additional “r” prepended to the usb partition name rdisk2 instead of disk2. The does a raw copy which is much faster than a block-by-block file copy.

Press CTRL + T to view progress, which will show blocks processed.

4177+0 records in
4177+0 records out
4379901952 bytes transferred in 323.733465 secs (13529346 bytes/sec)

Screenshot of the usb drive after iso has been copied. Note that the partition type has been changed to “0xEF” a GUID partition.

OSX will not recognise this partition, click ignore at the “Disk not readable” prompt. This usb drive will not be readable on OSX but can be used to boot and install CentOS 7.