Backup on Time Capsule and external harddisk

I suggest that you first get back ups going again on the Time Capsule, then we can discuss adding the USB drive as a second back up source.

For now, please power off and disconnect the USB drive from the Time Capsule.

On your Mac......open System Preferences (gear icon on the dock), then open Time Machine

Make sure that Time Machine is ON

Click Add or Remove Disks

Under Backup Disks, make sure that the Time Capsule disk (named "Data", unless you have changed the name) appears

If it does not, then click on Data under Available Disks

Then, click Use Disk

Close the window and now click on the Time Machine "clock" icon at the top of the screen

Click Backup Now, and that should get backups going on the Time Capsule again

Post back when you have confirmed that this is the case

Power off the Time Capsule by pulling the power cord from the back of the Time Capsule

Count to ten

Plug the power cord back into the back of the Time Capsule

Wait a few minutes, then try another backup

If the backup to the Time Capsule completes correctly, now you are ready to set up Time Machine backups to the external drive that is connected to the USB port on the Time Capsule.

Start again as we did above by opening System Preferences and then opening Time Machine

Click Select Disk

Select the name of the external drive from the list of Available Disks

Click Use Disk

When you are asked if you want to replace the Time Capsule (Data) with the external disk, choose the option to Use Both Disks

Now Time Machine will automatically alternate backups between the Time Capsule and the external drive, so you will have backups on both the Time Capsule and the external drive

If you have the Time Capsule now backing up,and you add the external drive to also back up, then you should see a message that looks like this example:

In the example above, my Time Capsule disk is named "Backups" and I am adding another external drive called "500GB Drive", so that Time Machine will take turns backing up to the Time Capsule and then the other drive.

Please try the following:

Power off the Time Capsule and the external drive

Wait a minute

Power up the Time Capsule for a minute, then power up the external drive and try the setup again.

The external drive that will be used for Time Machine backups must be formatted in Mac OS Extended (Journaled), which is also known as HFS+.

Do you know if your external drive meets this requirement?

Most hard drives that are sold at stores are for use on Windows and PCs. This type of drive cannot be used for Time Machine backups unless it is first formatted correctly for Mac.

As a test......what happens if you connect the external hard drive directly to your Mac.....not to the Time Capsule.....and try to set up Time Machine backups that way?

If the backup does begin......you can cancel and stop the backup unless you want to go ahead and back up your Mac to have another copy of your Mac.

Then, there are several possibilities:

1) The USB port on the Time Capsule is not working correctly

2) Your external drive might be a USB 3.0.....and the USB port on the Time Capsule is USB 2.0. USB 2.0 is supposed to be compatible with USB 3.0, but I have found that this is not true on my network, and a number of other users have compatibility issues with this as well.

3) The USB 2.0 port on the Time Capsule is underpowered, so it is often necessary to use a powered USB hub with the Time Capsule.....even if the hard drive has its own power supply.

I do not know what the exact answer to your problem might be, but it is probably one of the possibilities listed above, or a combination of the possibilities above.