We had upgraded from CDH 3u4 to CDH 4.2.0.
After the upgrade the namenode namedir is getting filled with edits files. Eventually filling up the namedir filesystem.
and making the namenode into safemode.
I am wondering if there is anything changed with respect to the fsimage and the editlogs parameters.
Check the NameNode log and see if you have exceptions in checkpoints.
This will cause checkpoints to not happen, which means old edits logs won't get purged.