mbrodmann commented on a change in pull request #85:
URL: https://github.com/apache/incubator-crail/pull/85#discussion_r578386001
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File path: namenode/src/main/java/org/apache/crail/namenode/BlockStore.java
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@@ -171,9 +192,33 @@ short addDataNode(DataNodeBlocks dataNode) {
return RpcErrors.ERR_OK;
}
-
+
+ short prepareForRemovalDatanode(DataNodeInfo dn) throws Exception {
+ // this will only mark it for removal
+ return prepareOrRemoveDN(dn, true);
+ }
+
+ short removeDatanode(DataNodeInfo dn) throws Exception {
+ // this will remove it as well
+ return prepareOrRemoveDN(dn, false);
+ }
+
//---------------
-
+
+ private short prepareOrRemoveDN(DataNodeInfo dn, boolean onlyMark)
throws Exception {
+ DataNodeBlocks toBeRemoved = membership.get(dn.key());
+ if (toBeRemoved == null) {
+ LOG.error("DataNode: " + dn.toString() + " not found");
+ return RpcErrors.ERR_DATANODE_NOT_REGISTERED;
+ } else {
+ if (onlyMark)
+ toBeRemoved.scheduleForRemoval();
+ else
+ membership.remove(toBeRemoved.key());
Review comment:
A datanode is only marked for removal first because it might still store
datablocks. Only when no data is stored anymore by a marked datanode the
namenode can start the actual removal process, that is removing it from its
datastructures and notifying the datanode that it can terminate (this is
periodically checked as part of the `getDataNode` RPC). When we just remove
that datanode the data it stores is not available anymore.
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