Learn about the error -9977 when creating an AppleRAID set, and a workaround to avoid the issue.
Symptom
An error -9977 may appear when using Disk Utility or diskutil to set up hard drives as part of an AppleRAID set.
Products affected
Solution
Warning: Always back up data you wish to keep before initializing a hard disk. Initialization erases all data on the hard disk.
When this issue occurs, the RAID set may appear to have been created and to be valid, but the file system is not valid. The file system is reported as ISO 9660.
Tip: If you are adding a drive to be rebuilt into a degraded mirrored RAID set and the replacement drive used to be part of the same or another RAID set, it must be erased before it can be added to the mirrored RAID set.