Unable to back up with Time Machine to internal drive on Mac Pro.

kenleym Said:

"Unable to back up with Time Machine to internal drive on Mac Pro.: Thank you for your help! Disk still not showing up in Time Machine, but does show in utilities. I mounted and unmounted 3 times and it is still not seen as an available disk in time machine. I have used that disk for other applications and it has worked. I do have an external that I can use with time machine and I'll continue with that. Thanks again"

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You are welcome.

External Drives for TMBs:

Using the external drive is the way to go about backing up your Mac. So, use that, rather than an internal one.

kenleym Said:

"Unable to back up with Time Machine to internal drive on Mac Pro.: I have an older Mac Pro with four internal drives. I use Time Machine for back up to an external drive, but I would like to back up to my already formatted internal drive. Time Machine does not show that drive as an option. How can I make that disk available?"

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Mount the Drive:

Boot into Recovery Mode (Hold Down: [Command + R] upon boot). Then, using Disk Utility, see if the Hard Drive is seem. If it is, then see if you need to click the “Mount’ button for it. Try rebooting once more. If of no success, then click unmount button, and then the mount button. Try rebooting once more.