1 Reply Latest reply: Nov 18, 2012 7:28 AM by Grant Bennet-Alder
Saint Dismas Level 1 Level 1 (0 points)

I have a Mac Pro with a 2 TB RAID (Two 2TB HDDs mirrored).  One of the HDDs says "Failed" next to it in the disk utility.  After making sure the data is backed up, can I just swap in a new drive?  Will the RAID see that the other half is blank and mirror the data onto the new blank drive?  Or will I have to restore from the backup after re-setting up the RAID with the one old drive and one new?


I want to say it's running 10.5 but it may be 10.6.   I can't be certain right now as I'm not in front of the system.



  • 1. Re: Mirrored RAID with one failed drive
    Grant Bennet-Alder Level 8 Level 8 (49,250 points)

    After you add in the new drive, it would be prudent to write Zeroes to every block to ensure data integrity. Those options are on the Security Options Button in the Erase tab in Disk Utility. This can be done in the background in your working System. It takes several hours as it is, More passes is not better.


    Then you need to Add the initialized drive to the running RAID set. Once it shows up as a Spare, you will be offered the option to "bring it up to date" in the background. This may take all day, but your Mac is still useable while it is doing this.


    The warnings at every step are un-necessarily dire. But if you cannot afford to lose data if something goes wrong, you SHOULD make a backup before proceeding.