Understanding the Use of Robocopy for File Copy Operations

Overview

Robocopy, short for "Robust File Copy," is a command-line utility in Windows used for copying files and directories, especially over networks and with advanced options. Below, we explain the two Robocopy commands you provided.

Command 1

robocopy "\\UNC_Path" C:\location /E /J /MT:75

·         \\UNC_Path: This is the source directory specified using a Universal Naming Convention (UNC) path, typically pointing to a network location.

·         C:\location: This is the destination directory on the local machine where files will be copied.

·         /E: Copies all subdirectories, including empty ones.

·         /J: Enables unbuffered I/O for large file copies, which can improve performance when copying large files.

·         /MT:75: Uses multithreaded copying with up to 75 threads, allowing multiple files to be copied simultaneously for faster performance. (The default is 8 threads if not specified.)

This command copies all files and subfolders from the network location (\\UNC_Path) to C:\location, including empty directories, using unbuffered I/O and up to 75 parallel threads.

Command 2

robocopy C:\location D:\location /E /J /MT:75

·         C:\location: The source directory on the local drive.

·         D:\location: The destination directory on another local drive (or partition).

·         /E, /J, /MT:75: Same as above.

This command copies all files and subfolders from C:\location to D:\location, including empty directories, using unbuffered I/O and up to 75 threads.

Summary Table

Best Practices & Cautions

·         Using a high number of threads (such as 75) can greatly increase copy speed, but may also put significant load on your system, especially for slower storage devices or network connections.

·         The /J switch is only available on Windows 8/Server 2012 and later.

·         Always verify the source and destination paths to prevent accidental overwriting or data loss.