INDEXTEST reads the entire index component of the KSDS cluster.
DATATEST reads the sequence set from the index component and the entire data component of the KSDS cluster. So, it should take considerably more time and more system resources than INDEXTEST.
If you are using EXAMINE to document an error in the data component, run both tests. If you are using EXAMINE to document an error in the index component, it is usually not necessary to run DATATEST.
If you are using EXAMINE to confirm a data set's integrity, your decision to run one or both tests depends on the time and resources available.