I have a mac laptop that I want to back up to an internal drive on my Mac Pro. The drive I want to back up to is blank and not the OS drive. They are connected via ethernet, but I do not see the drive on my computer. How would I be able to recognize it?
You have two options to allow Time Machine on your Mac to use an internal drive on another Mac Pro as the destination for normal backups from your MacBook.
Neither is a great option, but here they are.
Since neither of these is a good option, you could also look at getting some free software like CrashPlan. This software would be installed on both computers and each could back up to the other (or you could only back the portable to the Pro - one way backup) and you could have all the files stored on the one drive.
The downside is it's not Time Machine - but it is quite solid software that many, many businesses depend upon for valuable data.
Sorry there isn't a quick - do this and that to make the Pro serve up a drive as a Time Machine destination - but hopefully one of the three options will let you work out a plan.
I routinely use Time Machine to back up a MacBook Air, a MacBook Pro, and several Mac minis to a Mac Pro with two 1.5 TB internal hard drives. It is relatively straightforward, but there is a caveat.
You need to have the following:
On your laptop, you need to connect to the shared volume on the Mac Pro. Look under the "Shared" category in the Finder side bar. If both machines are on the same subnet, Bonjour should automatically make the Mac Pro visible. If they are on different subnets, you may need to connect manually. In this case, select "Go->Connect to Server" in the Finder (cmd-K) and enter "afp://macpro.example.com/". (Obviously you need to use your Mac Pro's actual domain name here.)
Once you have mounted the shared drive, go into System Preferences and select Time Machine. In the preference pane, click "Select Disk...". Your mounted volume should now appear as an option for Time Machine backups. Go ahead and select it.
Make sure to keep the remote volume mounted while Time Machine makes its first backup. Time Machine will prompt you for the username and password to store in the Keychain so that it can mount the disk on its own for future backups.
For future backups, Time Machine will automatically mount the remote volume using the credentials you provided, make a backup, and then disconnect the volume. There is no more work on your part.
When you need to recover a file, "Enter Time Machine" as you normally would. Time Machine will automatically mount the remote disk (assuming it is available) and go into file recovery mode. It will be slower than a locally connected disk, but it will work.
Although Time Machine will work normally, there is an important difference if you need to make a complete recovery from the Time Machine backup on the Mac Pro. In my case, for example, my MacBook Pro fell off a table and hit a hardwood floor, which damaged the internal hard drive. Once I got a new hard drive installed, I needed to recover from the Time Machine backup on my Mac Pro.
At the time, I had the OS X install disk, but the following comments should also apply to recovery disk mode under Lion. When going through the recovery process, the installer will ask if you want to restore from a Time Machine backup. Unfortunately, you will not find your backup disk in the list. The problem is that the volume you want to use is not available because the Mac Pro is not running OS X Server and is not broadcasting that it is a "Time Capsule". (See bmike's first bullet in his answer to this question.) The solution is to bring up a terminal window and manually mount your Time Machine backup on the command line. See the mount_afp manual page for documentation on how to do this.
Once you have the remote disk mounted, go through the normal recovery process. Your Time Machine backup should now be available as an option. It can take several hours to do a full restore over a network connection like this. In my case, I was able to fully recover from the accident.
I hope this helps.