HDFS-13728. Disk Balancer should not fail if volume usage is greater than capacity. Contributed by Stephen O'Donnell.

(cherry picked from commit 6677717c689cc94a15f14c3466242e23652d473b)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/diskbalancer/datamodel/DiskBalancerVolume.java

@@ -21,9 +21,10 @@ import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.ObjectReader;
-import com.google.common.base.Preconditions;
 
 import org.apache.hadoop.hdfs.web.JsonUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 
@@ -35,6 +36,9 @@ public class DiskBalancerVolume {
   private static final ObjectReader READER =
       new ObjectMapper().readerFor(DiskBalancerVolume.class);
 
+  private static final Logger LOG =
+      LoggerFactory.getLogger(DiskBalancerVolume.class);
+
   private String path;
   private long capacity;
   private String storageType;
@@ -269,10 +273,13 @@ public class DiskBalancerVolume {
    * @param dfsUsedSpace - dfsUsedSpace for this volume.
    */
   public void setUsed(long dfsUsedSpace) {
-    Preconditions.checkArgument(dfsUsedSpace < this.getCapacity(),
-        "DiskBalancerVolume.setUsed: dfsUsedSpace(%s) < capacity(%s)",
-        dfsUsedSpace, getCapacity());
-    this.used = dfsUsedSpace;
+    if (dfsUsedSpace > this.getCapacity()) {
+      LOG.warn("Volume usage ("+dfsUsedSpace+") is greater than capacity ("+
+        this.getCapacity()+"). Setting volume usage to the capacity");
+      this.used = this.getCapacity();
+    } else {
+      this.used = dfsUsedSpace;
+    }
   }
 
   /**

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

@@ -224,4 +224,20 @@ public class TestDataModels {
     Assert
         .assertEquals(cluster.getNodes().size(), newCluster.getNodes().size());
   }
+
+  @Test
+  public void testUsageLimitedToCapacity() throws Exception {
+    DiskBalancerTestUtil util = new DiskBalancerTestUtil();
+
+    // If usage is greater than capacity, then it should be set to capacity
+    DiskBalancerVolume v1 = util.createRandomVolume(StorageType.DISK);
+    v1.setCapacity(DiskBalancerTestUtil.GB);
+    v1.setUsed(2 * DiskBalancerTestUtil.GB);
+    Assert.assertEquals(v1.getUsed(),v1.getCapacity());
+    // If usage is less than capacity, usage should be set to the real usage
+    DiskBalancerVolume v2 = util.createRandomVolume(StorageType.DISK);
+    v2.setCapacity(2*DiskBalancerTestUtil.GB);
+    v2.setUsed(DiskBalancerTestUtil.GB);
+    Assert.assertEquals(v1.getUsed(),DiskBalancerTestUtil.GB);
+  }
 }