fix corrupted external RAID array on Mac

If you were able to run First Aid on the drives individually and can access them individually, you may need to restart or reconfigure the RAID enclosure to get it working again (you'll we need to check the manufacturers manuals on ho to do this).

The question becomes are you using a hardware RAID feature or did you use Disk Utility or some other macOS app to create the RAID? And what file system did you choose for the RAID? APFS is a new file system that is still experiencing growing pains and tends to become damaged where First Aid is unable to repair it, but AFPS should be less likely to become corrupt from a power failure. Unfortunately there are currently no third party utilities to repair an APFS volume since Apple still has not released the necessary APFS documentation. HFS+ (aka MacOS Extended) file system volumes can be repaired using the paid third party app Disk Warrior which has been around for nearly 20 years and does an excellent job repairing the HFS+ file system when First Aid cannot (assuming there are no hardware issues).

Depending on the RAID enclosure, you may be able to check the health of each drive in the enclosure. Some enclosures provide access to the drive's SMART health attributes either through the enclosure's management interface or other times you may be able to use DriveDx to check the health of a drive if the RAID enclosure does not block access to each drive's health information.

dig.photographer wrote:

I have a 24TB RAID array. We had 3 power failures in a 10 minute time frame. The array was on when the power failures occurred. Now, it won't mount.

You should look into getting a UPS for the RAID and the computer so you can safely unmount the volume and cleanly shutdown the computer.

When I run First Aid in disk untility, it fails to fix the corruption. It seems to indicate the container device is corrupted.

Within Disk Utility click "View" and select "Show All Devices" so that the hidden Container appears on the left pane of Disk Utility. Then run First Aid on the Container. Even if First Aid says everything is "Ok" click "Show Details" and scroll back through the report to see if there are any unfixed errors listed. If there are any unfixed errors listed, then you will need to erase the whole physical RAID set and restore from a backup assuming it is an APFS volume. If it is an HFS+ volume (aka MacOS Extended), then you can try running Disk Warrior (third party paid app that does an excellent job repairing HFS+ volumes) on the RAID volume to see if it can be repaired.