When the Time Machine window opens, initially, it will be set to off. Time Machine keeps:
The oldest backups are deleted when your disk becomes full.
If there are any files you wish to exclude from being backed up, click on the Options button and then select them. At the options window, you can also choose to deselect being notified after old backups are deleted. If the Options button is grayed out, click on the closed padlock icon you will see at the lower left-hand corner of the window and provide username and password credentials when prompted, which will change the icon to an open padlock and allow you to make Time Machine settings changes.
At the Time Machine window, click on the Select Backup Disk button. If you've already attached an external drive you wish to use for the backup, but you only see a "Other Time Capsule", then Time Machine doesn't recognize the drive is attached.
If you've connected an external drive to use for a backup and it doesn't appear, it may not be formatted. If you need to format the drive use the Disk Utility application found in the Applications/Utilities folder and format the drive with Disk Utility. But you may first want to reseat the USB cable on both ends to make sure it is firmly seated at the disk drive and computer ends.
When you see the drive listed, you can click on it to select it and then click on the Use Disk button. E.g. in the screen shot below the external drive connected by a USB cable is a 500 GB drive labelled "MacBook Pro Backups".
When you do so, you should see the Time Machine button go from "OFF" to "ON" in the Time Machine window and you should see a countdown to the next backup appear to the right of Select Disk.
When the countdown timer gets to zero, the first backup should start and you should see a continual status update on how much data has been backed up so far out of the total amount to be backed up.
You can continue to use the system while the backup is running. If you open the Time Machine app later, you will see dates and times for the oldest, latest, and next backup.
If you click on the Options button, you will see that Time Machine automatically added the backup device to the list of items to be excluded when it conducts a backup.
When you need to disconnect the external drive you are using for Time Machine backups, you can do so through the Finder by selecting File then Eject. If you simply disconnect the cable, you will be warned that "The disk was not ejected properly. If possible, always eject a disk before unplugging it or turning it off."
Created: Tuesday July 7, 2015
