[ http://issues.apache.org/jira/browse/HADOOP-124?page=comments#action_12374091 ]
Doug Cutting commented on HADOOP-124: ------------------------------------- I just talked with Owen, and we came up with the following plan: (0) store a node id in each dfs.data.dir; (1) pass the node id to the name node in all DataNodeProtocol calls; (2) the namenode tracks datanodes by <id,host:port> pairs, only talking to one id from a given host:port at a time. requests from an unknown host:port return a status that causes the datanode to exit and *not* restart itself. (3) add a hello() method to DataNodeProtocol, called at datanode startup only. this erases any entries for a datanode id, replacing them with the new entry. Thus when a second datanode is started it causes any existing datanode running on that host to be forgotten and to exit when it next contacts the namenode. > don't permit two datanodes to run from same dfs.data.dir > -------------------------------------------------------- > > Key: HADOOP-124 > URL: http://issues.apache.org/jira/browse/HADOOP-124 > Project: Hadoop > Type: Bug > Components: dfs > Versions: 0.2 > Environment: ~30 node cluster > Reporter: Bryan Pendleton > Priority: Critical > > DFS files are still rotting. > I suspect that there's a problem with block accounting/detecting identical > hosts in the namenode. I have 30 physical nodes, with various numbers of > local disks, meaning that my current 'bin/hadoop dfs -report" shows 80 nodes > after a full restart. However, when I discovered the problem (which resulted > in losing about 500gb worth of temporary data because of missing blocks in > some of the larger chunks) -report showed 96 nodes. I suspect somehow there > were extra datanodes running against the same paths, and that the namenode > was counting those as replicated instances, which then showed up > over-replicated, and one of them was told to delete its local block, leading > to the block actually getting lost. > I will debug it more the next time the situation arises. This is at least the > 5th time I've had a large amount of file data "rot" in DFS since January. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
