I was trying to create bootable USB of Ubuntu 17.04. First, I erased everything from the pen drive and then started to copy using sudo dd if=path_to_ubuntu_image of=/dev/rdisk2 but it is taking around 5 hrs to complete the process. I read previous answers about speeding up it using rdisk instead of disk but I was initially using that only. There was to use bs but I have doubt will it bring some change in the bootable image while copying ? Please help.
Size of Ubuntu - 1.63GB
I am using the latest version of macOS High Sierra.

Link of webpage whom steps I was following - http://courses.cms.caltech.edu/cs171/materials/pdfs/How_to_Dual-Boot_OSX_and_Ubuntu.pdf


1 Answer 1


The default block size is only 512 bytes, which significantly cripples the transfer rate. You should use a block size that is a much, much larger.

OSX Daily has step by step instructions, they suggest 1 MB, but you might want to try even larger.

sudo dd if=/path/image.iso of=/dev/r(IDENTIFIER) bs=1m 

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