Fixing Disk Utility image restore

For some reason, restoring a DMG image to a block device has been an atypically frustrating experience under Mac OS X (since Leopard – 2007). Apple Disk Utility comes back with user unfriendly errors citing an ‘invalid argument’. It insists on doing some silly ‘image scan’ which never actually works, thereby blocking any successful image restore. Delving deeper I thought it was likely some other component utilized by Disk Utility was failing and I found what it was.

It turns out that Disk Utility employs Apple’s ASR utility, stored at

/usr/sbin/asr

To learn more you can run ‘asr’ by itself in Terminal. While

man asr

shows a lot more, I’ll save you from reading that (this man page has even got a History section).

Simply restore without an image scan:

$ sudo asr -noverify -source source -target target