6027-908 [W] Attention: In RULE 'ruleName' (ruleNumber), the pool named by "poolName 'poolType'" is not defined in the file system.
Explanation
The cited pool is not defined in the file system.
User response
Correct the rule and reissue the command.
This is not an irrecoverable error; the command will continue to run. Of course it will not find any files in an incorrect FROM POOL and it will not be able to migrate any files to an incorrect TO POOL.