Software that compares directories and backup/sync only modified files

Question

Is there a free software that will compare my D drive with my USB backup hardrive and copy/replace only the modified/newly created files to it? Windows 10 64 bits here.

Answer 1

Robocopy can do this.

It's already built into Windows 10 so all you need to do is invoke it from Command Prompt or use a batch file.

Let's assume:

D drive = data drive.

E drive = USB drive.

Use this syntax if you have subfolders:

robocopy /e "d:\source data folder" "e:\USB backup folder" /r:1 /w:1

Alternatively, use this syntax if you want to specify the root of your drives:

robocopy /e d:\ e:\ /r:1 /w:1

/e includes subdirectories and Empty subdirectories. By default, only files are included and not any subdirectories.

/r:1 Retries locked files 1 time.

/w:1 Waits 1 second before reattempting locked files.

• If either the Size or the Last Modified dates differ between any given source and corresponding destination file then a destination file will be overwritten by the source file.

• Newly-created files will be included.

• Files deleted from the source will not be deleted from your USB drive. This behaviour can be changed by including the /mir (MIRror) switch:

robocopy /mir "d:\source data folder" "e:\USB backup folder" /r:1 /w:1

• /e is redundant if /mir is used as the entire directory tree in the source will already be included.