I have to replace one of my disk so I put another on the array to takes its place.  I started copying the data by external pc by moving the data from one disk to the other disk in my network places.  Then I realized this will take forever cause it is going over the network.  Is there a command line that I can type in unraid server itself to internally move the data? And potentially saves hours?  I am currently using the beta version of unraid.

To understand the process and commands, see the How-To's for pages that help with mounting drives and transferring files.

 

But also check out UnMENU (an UnRAID Add On).  It facilitates the mounting of other drives.

Why not swap the drive right out, and let the parity rebuild the new disk? The old disk will still have the data if something happens...