On my mac cp command works 9 times faster then mv. Why it is possible?

Mac-Pro-AVM-4:2014-10-22 editor$ time cp /Volumes/AVM4_HD5/INGEST/Final\ Cut\ Original\ Media/2014-10-22/Clip\ \#13.mov /Volumes/VIDEO1/MATERIAL/327/Source/sd3 

real    0m4.466s
user    0m0.002s
sys 0m0.214s
Mac-Pro-AVM-4:2014-10-22 editor$ time mv /Volumes/AVM4_HD5/INGEST/Final\ Cut\ Original\ Media/2014-10-22/Clip\ \#13.mov /Volumes/VIDEO1/MATERIAL/327/Source/sd3 

real    0m36.091s
user    0m0.032s
sys 0m1.378s

Finder also moves this file in 4-5 seconds. AVM4_HD5 - local HDD, VIDEO1 - smb mounted RAID, OS X 10.9.5.

  • move has to check arrival then delete the original, copy is relatively 'cheap' if there's a fail. Replace is slowest of all.
    – Tetsujin
    Dec 19, 2014 at 19:27

1 Answer 1


Tetsujin is right; in this case, a move copies, then deletes the original. There are also a couple things I want to add.

First, that only applies when moving between volumes. If you're moving from one place to another on the same volume, then a move will be nearly instant because it only needs to change a small amount of data that specifies where the file is located; it doesn't actually move the file data. On the other hand, copy has to duplicate the data itself. If you're moving from one volume to another, copy and move both have to copy the data, but move has the extra task of deleting the original.

Second, remember that Final Cut Pro X uses aliases to reference the media. Be careful when you move or copy, and be sure you know what file the aliases are actually pointing to. You probably already know that though. :)

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