When starting Hadoop on OS X 10.7 ("Lion") using start-all.sh, Hadoop logs the following errors:
2011-07-28 11:45:31.469 java[77427:1a03] Unable to load realm info from SCDynamicStore
Hadoop does seem to function properly despite this.
The workaround takes only 10 minutes.
There are numerous discussions about this:
google "Unable to load realm mapping info from SCDynamicStore" returns 1770 hits. Each one has many discussions.
Assume each discussion take only 5 minute, a 10-minute fix can save ~150 hours. This does not count much search of this issue and its solution/workaround, which can easily hit (wasted) thousands of hours!!!