# Backing up to an external disk

A very frequent use of Synk is to backup an important directory, like your home folder, to an external disk.

## To backup a directory to an external disk:

1. Drag the directory you want to back up from the Finder to the "Source A" area of the document window
2. Plug in your external disk. Choose the target of your backup, and drag it to the "Source B" area of the document window.
3. Select the "Backup A to B" option.
4. If desired, change settings on the other tabs to meet your needs. More information on these settings is available elsewhere in Synk Help.
5. Save the document.

Now, whenever you wish to back up your folder, simply plug in your external drive, open the Synk document, and click "Run." Any changes you made to the directory will be automatically reflected on the external drive.

You can also instruct Synk to automatically back up the folder at particular times. (Your external disk will need to be mounted at the time specified.) Learn more about scheduling.

If you want to back up a folder that is outside of your own home folder, such as the entire disk, you will need to run Synk as root. Learn how to run Synk as root.