Although by default CVU reports in nonverbose mode by only reporting the summary of a test, you can obtain detailed output by using the -verbose argument. The -verbose argument produces detailed output of individual checks and where applicable shows results for each node in a tabular layout.
If a cluvfy command responds with UNKNOWN for a particular node, then this is because CVU cannot determine whether a check passed or failed. The cause could be a loss of reachability or the failure of user equivalence to that node. The cause could also be any system problem that was occurring on that node when CVU was performing a check.
The following is a list of possible causes for an UNKNOWN response:
The node is down
Executables that CVU requires are missing in Grid_home/bin or the Oracle home directory
The user account that ran CVU does not have privileges to run common operating system executables on the node
The node is missing an operating system patch or a required package
The node has exceeded the maximum number of processes or maximum number of open files, or there is a problem with IPC segments, such as shared memory or semaphores