We have released a set of articles that contain information about troubleshooting the "failed" disk status, as reported by vxdisk.
Here is the link:
"Failed" or "failed was" is reported by vxdisk
Since this is a broad topic, the "technote" is actually a set of about a dozen article that have been organized into a logical tree structure, with TECH200618 at its "root."
Let us know what you think!