Ming Ma created HDFS-6626:
-----------------------------
Summary: Node is marked decommissioned if it becomes dead when it
is being decommissioned
Key: HDFS-6626
URL: https://issues.apache.org/jira/browse/HDFS-6626
Project: Hadoop HDFS
Issue Type: Bug
Reporter: Ming Ma
Not sure if it is by design. But it isn't intuitive. The scenario is like this,
you try to decommission a node; when the node is being decommissioned, the node
becomes dead from NN's point of view; right after that NN will mark this node
decommissioned. On the webUI, administrators will consider the decommission has
completed successfully. That is because when there is no block left for the DN,
decommission is considered done.
{noformat}
BlockManager.java
boolean isReplicationInProgress(DatanodeDescriptor srcNode) {
boolean status = false;
...
final Iterator<? extends Block> it = srcNode.getBlockIterator();
while(it.hasNext()) {
...
// set status if there is block under replication
}
...
return status;
}
{noformat}
The question is whether we should mark the dead node as decommission completed
(the current behavior), or mark the dead node "decommission aborted". From
administrators' point of view, when they are doing decomm, they want to know
the status of decomm and the health of those decomm-in-progress nodes. If they
can detect decommission failure earlier, they might be able to take actions
earlier; for example if the TOR switch has issues during decomm, administrators
will be able to quickly find out a bunch of "decommission aborted" nodes from
the same rack. People can still find this information by doing the join between
decomm node list and recent dead node list on the webUI; just not as convenient.
Suggestions?
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