HDFS-15438. Setting dfs.disk.balancer.max.disk.errors = 0 will fail the block copy. Contributed by AMC-team.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DiskBalancer.java

@@ -902,7 +902,7 @@ public class DiskBalancer {
      */
     private ExtendedBlock getBlockToCopy(FsVolumeSpi.BlockIterator iter,
                                          DiskBalancerWorkItem item) {
-      while (!iter.atEnd() && item.getErrorCount() < getMaxError(item)) {
+      while (!iter.atEnd() && item.getErrorCount() <= getMaxError(item)) {
         try {
           ExtendedBlock block = iter.nextBlock();
           if(null == block){
@@ -923,7 +923,7 @@ public class DiskBalancer {
           item.incErrorCount();
         }
       }
-      if (item.getErrorCount() >= getMaxError(item)) {
+      if (item.getErrorCount() > getMaxError(item)) {
         item.setErrMsg("Error count exceeded.");
         LOG.info("Maximum error count exceeded. Error count: {} Max error:{} ",
             item.getErrorCount(), item.getMaxDiskErrors());

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/diskbalancer/TestDiskBalancer.java

@@ -757,7 +757,7 @@ public class TestDiskBalancer {
         }
       }, 1000, 100000);
 
-      assertTrue("Disk balancer operation hit max errors!", errorCount.get() <
+      assertTrue("Disk balancer operation hit max errors!", errorCount.get() <=
           DFSConfigKeys.DFS_DISK_BALANCER_MAX_DISK_ERRORS_DEFAULT);
       createWorkPlanLatch.await();
       removeDiskLatch.await();