HDFS-10588. False alarm in datanode log - ERROR - Disk Balancer is not enabled. Contributed by Weiwei Yang.

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

@@ -294,7 +294,6 @@ public class DiskBalancer {
   private void checkDiskBalancerEnabled()
       throws DiskBalancerException {
     if (!isDiskBalancerEnabled) {
-      LOG.error("Disk Balancer is not enabled.");
       throw new DiskBalancerException("Disk Balancer is not enabled.",
           DiskBalancerException.Result.DISK_BALANCER_NOT_ENABLED);
     }