R P
posted this
09 November 2016
Hi Charles,
The problem is the drive contains DDF (Disk Data Format, raid metadata). Windows won't do anything with the disk either and gives a wierd error message I don't recall.
Your MAC has the ability to clean the metadata, but you will have to use the terminal, sudo, and the 'dd' command (also known as disk destroyer). You must be extremely careful with this command or you can delete the contents of a disk you want to keep.
I suggest the following, open a terminal, and with the disk you want to clean *not* attached run the following command.
diskutil list
This will show you what disks you don't want to touch. Then attach the disk you want to clean and run the same commad again. This will allow you to tell for certain which drive device is the one you want to delete the contents of, it will be the difference between the first and second listing. Also the raid disk should not show any Apple_HFS or Apple_Boot partitions.
/dev/disk0 will probably (but not necessarily) be your boot disk, if you added the disk to a running OS with a USB dock, the device added will be the last disk device, let's say it's /dev/disk2 as an example. The command to clean that disk would look like this...
sudo dd if=/dev/zero of=/dev/disk2 bs=100m
This will write nulls till the end of the disk (where the DDF is) then error out. For a 2TB it can take several hours, it won't be fast.
Be very careful with this, double check to be sure you know which disk is the old RAID disk you want to clean, and unfortunatly, this is at your own risk. 'dd' does not ask for confirmation, once you hit return it runs, so you need to get it righ the first time.
Regards,
--Rich
