Backup drives?

Hello,

Please refer to the following Apple support document. It sounds like you need to replace your older external hard disk in Time Machine preferences with your new external hard disk.

Using Time Machine

Time Machine preferences, choose

Apple menu > 

System Preferences,

then click Time Machine.

Try turning it off and on -- if nothing

Click lock to make changes -

click on select disk and remove.. by selecting and hitting minis - button

restart Mac

Then plug it back in and switch on time machine

make sure your drive is 2 times the size of your existing one too.

There are several possible reasons for your problem. First, assuming the drive is constantly attached to the computer, TimeMachine makes a backup every hour. When space runs out TM will need to erase older data for the new backup. Sometimes TM is unable to delete enough space. This is why we recommend the TM drive be at least 2 times larger than the data being backed up and preferably larger. For example, my desktop computer has a bit more than 400GB of data - my TM backup is a 2TB drive. It will be a long time before anything needs to be deleted and when that happens what is deleted will be more than a year old. If your TimeMachine drive isn't much larger than the data being backed up you'll need to purchase a drive that is more inline with what I described.

TimeMachine can also stall if in the middle of the backup the computer is quit, put to sleep, or crashes. Actually TM is very resilient and can often pick up where it left off, but sometimes it does stall. Open the TM drive, click on the TimeMachine backup folder, then on the computer's folder, and look for a file called InProgress. If you see that file, open up TimeMachine preferences and turn TimeMachine off. Then drag the InProgress file to the trash, empty the trash, and turn TM back on. See if that solves the problem.