661      iPhone_iPad_Mac_apple

The disk I inserted is not readable(partition m...

I'm trying to add more storage/backup/update my Macbook Pro Retina, 13-inch, Late 2013 OS X 10.9.5 using a hard drive, but when I plug it in a window pops up saying "The disk you inserted was not readable by this computer." and give me the option to "Ignore" "Eject" and "Initialize...". When I choose Initialize it opens Disk Utility. In Disk Utility I click "Verify Disk" but an alert pops up say "Partition map check failed because no slices were found." and the history shows:

Verifying partition map for “WD My Passport 2599 Media”

Checking prerequisites

Checking the partition list

Problems were found with the partition map which might prevent booting

Error: Partition map check failed because no slices were found.

so I then try "Repair Disk" and get the same alert and the history shows:

Verifying and repairing partition map for “WD My Passport 2599 Media”

Checking prerequisites

Checking the partition list

Problems were encountered during repair of the partition map

Error: Partition map check failed because no slices were found.

your question can’t be answered yet. In Finder, press Command-Shift-U to open the Utilities folder, and run Terminal in there. In the Terminal window, give it the following commands, one per line, pressing the Return key at the end of each line:

diskutil list

diskutil cs list

mount

Please include in your reply the full output from these commands.