reformatting an external hard disk
I recently bought a second external hard disk. The box said it would need to be reformatted for Mac. I tried using disk utility. It wouldn't backup from time machine. I searched previous questions and found this:
Drive Partition and Format
1. Open Disk Utility in your Utilities folder.
2. After DU loads select your external hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed.
4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.
6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.
But that still didn't work. I keep getting this error message:
"The backup was not performed because an error occurred while copying files to the backup disk. The problem may be temporary. Try again later to back up. If the problem persists, use Disk Utility to repair your backup disk."
I've gotten this message 4 times. It's a 2007 macbook pro, running 10.7.5. USB 2 (hard disk says usb 3.0 + usb 2.0).
thanks for any help you can provide