When topology.node.switch.mapping.impl is set to enable rack-locality resolution via the topology script, from the RM web-UI, we can see the rack information for each node. Running a job also reveals the information about rack-local map tasks launched at end of job completion on the client side.
But the hostname field for attempts in the JobHistory does not contain this rack information.
In case of hadoop-0.20 securiy or MRV1, hostname field of job history does contain rackid/hostname whereas in MRV2, hostname field only contains the hostIP. Thus this is a regression.