>> In prepareDirToFail it says the file is set to perms "000" but File#createNewFile uses the default perms (eg 644 with umask 022), so it should still be accessible right?
No. The comment was wrong. I replace the directory with a file so that DiskChecker.checkDirs() will fail because it tries to do mkdir with the same name and this will be reported as a disk failure. Updating the comment accordingly.
>> If you want not always have waitForDiskHealthCheck wait for 10s at a time seems like you can lower the DISK_HEALTH_CHECK_INTERVAL to eg 1s.
OK. Changing to 1 sec.
>> Would also be good to test startup with a failed directory. Feel free to punt this to
This change would need a handle into the code of MiniMRCluster.TaskTrackerRunner() and needs some refactoring and exposing some api in MiniMRCluster. So not doing it as part of current JIRA.