iMac & external hard drive question

Discussion in 'iMac' started by johnlandino, Jan 14, 2016.

  1. johnlandino macrumors member

    Oct 25, 2009
    i recently purchased a WD 4TB My Book external hard drive to back up my mac. however after setting it up i realized that what i wanted to do was not use it as so much of as back up, but use it as a place to move data and free up my 2008 imac's internal available space so that it will run faster and operate better.

    as we all know, using the external hd with time machine means my internal hard drive is duplicated and copied to my external hd. but recently, i turned off time machines automatic updates and started deleting files like music, movies, and pictures from my internal hd and letting them only exist on the external drive.

    so my question is, if i turn time machines automatic updates back on, will these files be then automatically deleted from my external hd? or will it only update and sync what new data is saved to my internal hd?
  2. MadDane macrumors 6502a

    Apr 5, 2015
    Time Machine only backs up what is on the target drive. In other words, it does not do anything to whatever other data there is on the drive where the backup is stored.

    Unless it is not that big of a deal with the data stored on the WD, I would advise you to acquire another external drive. That way you would have one for storing data and one solely used for backups. By using the same disk for backup and data, you risk losing all of the data that is stored only there if the WD kicks the bucket. Also be aware that Time Machine uses all available disk space. So at some point you will run out of space on the WD, unless you partition the drive. One part for storage and one for backups. But as I said, I would recommend keeping storage and backup on two physically different drives.
  3. johnlandino thread starter macrumors member

    Oct 25, 2009
    i do not have the money or the desk space for another external drive. the files on my mac are not that important to back up. all i want to do is free up space on my internal drive by moving it all to my external drive and keeping it there. more or less using it just as a large flash drive.

    how do i do this?
  4. MadDane macrumors 6502a

    Apr 5, 2015
    Okay, I think I am understanding what you are trying to do. You had a bunch of files on your iMac that now only exists on the WD in the Time Machine backup because you deleted them from your iMac. Is that correct?

    Assuming that I understood your question correctly, then Time Machine will only delete the old files when it runs out of space on the external hard drive. What will then happen is that it warns you that the disk is full, and asks if it can delete the oldest data.

    What I would suggest that you do instead of leaving it in the Time Machine folder is simply to move the files from the backup location into a different folder on the WD. That way the files will not be deleted, even if you decide to turn Time Machine on again in the future. An example for how to do this could be:
    - Locate a file in the Time Machine backup, for example a movie
    - Create a new folder on the WD called 'Movies'
    - Move movie from Time Machine folder to the 'Movies' folder

    Using the above, Time Machine will not overwrite the data if you decide to turn it on again.
  5. JustMartin macrumors 6502a

    Feb 28, 2012
    Time Machine uses a different structure for storing its data, so it won't overwrite your external copy of an internal file when it does a backup.

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