Backup Failed - not enough space on Mac HD

Replace the EHD with a larger capacity drive as a last resort. However TM will automatically remove the oldest backups to ensure it does not run out of space.

If you decide on a larger capacity drive I recommend OWC (www.macsales.com) Mercury Elite Pro series. You can move your old backups to the new drive. If you need help with that then simply ask.

 

The only reason I'd consider suggesting OWC is if you HAVE to have Thunderbolt connectivity. There are PLENTY of other manufacturers out there that make quality drives that cost less than you'd pay at OWC. For example, the 2 TB WD MyPassport Ultra is $86 on Amazon (I have this exact drive) while the 2 TB OWC Mercury 2 TB USB 3.0 is $150.

 

How much space do you have left on the disk you are trying to back up -- the MBP? I think what might be happening here is your hard disk is nearly full.

 

You have two disks labeled "Macintosh HD". One external, one internal. Presumably you want to backup onto "Back up".

Here's my set up. (Yeah, I'm a whovian)



when I click select disk, here's what shows up.



Any obvious discrepancies? Such as backing up onto the external "Macintosh HD" disk instead of the "Back up"?

Also, you probably should click "Details" on that Time machine error.

 

In the Time Machine Preference, click Select disk. Highlight the 320 GB Macintosh HD. Click Remove Disk. Click "Stop Using this disk."

 

That would be the sheet that pops down when you press the "Options" button.
You need to press the "Select Disk" button.