Q: How do get past the error: "partition failed: couldn't unmount disk"
My external hard drive is not formatted properly and is stuck where it can only read files and not write. Thus, I am unable to add files to my external drive. There is no option when I choose to get info to unlock the sharing and permissions and that area has no other option it simply says, "you can only read." I found an apple post showing how to essentially erase and re-format to MAC OS X extended but then I get the following error listed below. Here is what comes up when I try to re-format my hard drive...I have tried both ways, see below:
MacBook Air, OS X Yosemite (10.10.5), null
Posted on Aug 29, 2015 7:30 PM
Start your computer from Recovery (holding down the Command and R keys) and erase and re-format to Mac OS Extended (HFS Plus) the Seagate volume.
Posted on Sep 4, 2015 3:45 PM

