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As easy as it is to set up Time Machine, what do you do if you accidentally make an external data HD a Time Machine backup when you didn't mean to? This is especially important since if you're using a Hard Drive for Time Machine you should not store other data files on it or else it may cause the drive to fail when it gets full.
To make sure your data Data Hard Drive is not configured as one of your Time Machine backup HDs:
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2b) You can go to the Apple-> System Preferences and then select on “Time Machine”.
3) Once the Time Machine Preferences Window is open, Click on “Select Disk”. When you do so it will show you a list of all the HDs connected to your Mac.
4) If you see your data hard drive listed there, select on it and see if the button in the lower right corner says “Use Disk”. Do NOT click on “Use Disk”. If it says “Use Disk” “Use Disk” it means that your data hard drive is currently NOT a Time Machine backup drive. If the button says “Remove Disk” “Remove Disk” it means your Mac DOES consider this a backup drive and so you should click on “Remove Disk” to remove it from your Mac using it as a Backup Drive if you don't want this hard drive to be a backup drive for Time Machine.
4a) It is important that you don’t accidentally remove your actual Time Machine backup drive by accident. If you see your actual Time Machine backup drive listed do not click “Remove Disk” or it will stop backing up.
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4c) After you change your Data Hard Drive’s name to something different, quit out of Time Machines Preferences and go back to step 2 to run Time Machine Preferences again. This time it should show the drives with different names.
5) The next time you connect your data hard drive to your Mac, the Mac may ask you something like “Do you want to use this disk as a Time Machine backup?” The answer is no. It should remember this going forward and never ask you this again.
As always, if you have any questions regarding Time Machine, please contact Albert or Dan or your SHASS IT liaison.