I started a DN on a machine that was completely out of space on one of its drives. I saw the following:
2012-02-02 09:56:50,499 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for block pool Block pool BP-448349972-172.29.5.192-1323816762969 (storage id DS-507718931-172.29.5.194-11072-12978
42002148) service to styx01.sf.cloudera.com/172.29.5.192:8021
java.io.IOException: Mkdirs failed to create /data/1/scratch/todd/styx-datadir/current/BP-448349972-172.29.5.192-1323816762969/tmp
but the DN continued to run, spewing NPEs when it tried to do block reports, etc. This was on the
HDFS-1623 branch but may affect trunk as well.