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I have a few folders that have files which I want to have back-up on a external disk.

Do you know an app that automatically synchronizes the contents of my folders with the contents of the folders on the disk, when I attach the disk (it's a usb memory stick) ?

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up vote 7 down vote accepted

Synctoy can accomplish that and more for you. One of the many advantages of Synctoy is that it allow for synchronizing files and also folders between different computers. It is a very useful tool specially for creating backups of files and folders. And also the best thing is that it is free.

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I think this is the most suitable solution for the OP. – paradroid Dec 17 '11 at 18:30

Robocopy is also very handy, if you are inclined to do things with batch scripts.

I find the /B switch particularly useful at times.

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robocopy is ridiculously slow. – user626528 Feb 3 '15 at 10:13

it's built into to windows - called briefcases.

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Briefcases are an abobination. They sync files, but not new files added to given folders. They are slow as hell since they "compact" your files into the briefcase file (I just tested, took 15 seconds to create a 100MB briefcase on a SSD drive and a i920 cpu, ridiculous!). And it doesn't sync automatically upon inserting a usb key. – mtone Dec 17 '11 at 19:04

I recommend you look intop Manuel's answer, Synctoy, since it is very simple to use and straightforward. Personally, I use the free and open-source FreeFileSync for it's more advanced settings, fast speed and batch file associations.

However, neither of those tool starts syncing automatically upon inserting a USB key.

1) Simple workaround technique:

My preferred way of dealing with external disk/key sync is to put a batch file on the root folder. Whenever I plug it in, the files appear and I double-click "sync.bat" or whatever. Very user-friendly compared to having to load up your syncing tool and run it - you'll never forget to start it!

Here's how to do it with SyncToy.

  1. Run Synctoy and create a folder pair. I called mine "test"

  2. Create a new file on your USB key and call it "sync.bat". Edit it in notepad and type the following:

    "c:\Program Files\SyncToy 2.1\SyncToyCmd.exe" -R test


  3. Save and try it.

With FreeFileSync:

  1. Use the Create batch function, create a profile and save it directly on your usb key. No need for a .bat file.

2) Automated technique:

I had looked into the problem a while ago, and managed to make it work by running a Windows Powershell script. If it's critical for you (syncing very often), I posted all my details in another answer HERE.

Since you asked for a "simple" solution, it might not be worth the trouble.

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any way to install FreeFileSync without Baidu antivirus? – user626528 Feb 3 '15 at 10:14

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