I upgraded my 2011 13" MBP from a 512GB to a 1TB HDD and created two partitions. This first partition is an image copy from the old HDD. The second partition is empty and formated for the Mac OS filesystem: /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk0 1: EFI 209.7 MB disk0s1 2: Apple_HFS Macintosh HD 499.6 GB disk0s2 3: Apple_Boot Recovery HD 650.0 MB disk0s3 4: Apple_HFS Macintosh HD 2nd 499.6 GB disk0s4 I recently upgraded the OS from Lion to Mountain Lion without any problems. Now I am running out of space on my main partition and would like to move my music and pictures libraries off to the second (slower) partition. However, I notice that the /etc/fstab file now indicates that it is no longer used. So I am leaving the mountpoint at /Volumes/Macintosh\ HD\ 2nd for now. (So side question, how can I setup a different mountpoint under my home account to prevent other users of my laptop from claiming that space besides setting directory permissions on the mountpoint?) When I try to mv the files from my home directory to the mounted location, I receive an error message: $ mv Pictures /Volumes/Macintosh\ HD\ 2nd/ mv: rename Pictures to /Volumes/Macintosh HD 2nd/Pictures: Permission denied I do have write access to that directory and was able to touch successfully. I could copy, delete and link, but I really want to understand why a move command is attempting a rename instead of copy/unlink when dealing with an operation across different volumes. I don't see any options in the man page. Why is mv failing?