Updating boot partitions required mac
My reference "The missing manual" does not cover this challenge.
I have used GNU ddrescue to copy a crashed WD external disk over to an identical one.
For information on UEFI-based systems, see Section 23.1.2, “Configuring a TFTP Server for UEFI-based AMD64 and Intel 64 Clients”.
The problem here is that disk utility is usually not smart enough to know when to give up.
And repairs can take a long time (overnight is not unheard of) so unrecoverably damaged disks often initially diagnose similar to what you are seeing.
4.- On the screen it will display you all the Disk it detects connected to your Mac select the one that got damaged partition tables and press Enter.
Now that OS X Yosemite is available, many users may wish to create a bootable installer drive from something like a USB flash thumb drive or another disk.