Disk Utility and Raid

[Jefferyd32]

I have been trying to set up a very basic Raid mirroring system. Over the past 6 months I slowly ripped all my DVD's in order to play on an AppleTV. I have about 2.5 TB of data, all stored on one HD. I just purchased a second 3 TB HD in order to back up my first external. When attempting to set up my Raid disk utility states that all data on both drives will be deleted. This will not work. Is there a way around this? Any suggestions? I don't want to have to purchase another 3 tb drive in order to put my data on while I set up my Raid. There must be some alternative. This is my first time setting up a raid system and quite frankly until recently when I lost a bunch of important data I had not even backed my files up at all.

 

[dknightd]

When you create a raid set with diskutility, you have to erase all disks.

A better alternative to raid might be manually backing up to the second disk. Using something like CCC (CarbonCopyCloner).

The biggest cause of data loss is human error. i.e. accidently deleting a file. Raid does not protect against this. Raid provides redundancy to prevent downtime - it should not be considered a backup.