diff --git a/hbase-it/src/test/java/org/apache/hadoop/hbase/test/IntegrationTestBigLinkedList.java b/hbase-it/src/test/java/org/apache/hadoop/hbase/test/IntegrationTestBigLinkedList.java
index a3a26d69fe1..fe097c5ab2b 100644
--- a/hbase-it/src/test/java/org/apache/hadoop/hbase/test/IntegrationTestBigLinkedList.java
+++ b/hbase-it/src/test/java/org/apache/hadoop/hbase/test/IntegrationTestBigLinkedList.java
@@ -51,9 +51,11 @@ import org.apache.hadoop.hbase.client.Put;
 import org.apache.hadoop.hbase.client.Result;
 import org.apache.hadoop.hbase.client.ResultScanner;
 import org.apache.hadoop.hbase.client.Scan;
+import org.apache.hadoop.hbase.client.ScannerCallable;
 import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
 import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
 import org.apache.hadoop.hbase.mapreduce.TableMapper;
+import org.apache.hadoop.hbase.mapreduce.TableRecordReaderImpl;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.io.BytesWritable;
 import org.apache.hadoop.io.NullWritable;
@@ -624,6 +626,8 @@ public class IntegrationTestBigLinkedList extends Configured implements Tool {
       job.setNumReduceTasks(numReducers);
       job.setJarByClass(getClass());
 
+      setJobScannerConf(job);
+
       Scan scan = new Scan();
       scan.addColumn(FAMILY_NAME, COLUMN_PREV);
       scan.setCaching(10000);
@@ -1065,4 +1069,10 @@ public class IntegrationTestBigLinkedList extends Configured implements Tool {
       job.getConfiguration().setInt(GENERATOR_WRAP_KEY, wrapMuplitplier.intValue());
     }
   }
+
+  private static void setJobScannerConf(Job job) {
+    // Make sure scanners log something useful to make debugging possible.
+    job.getConfiguration().setBoolean(ScannerCallable.LOG_SCANNER_ACTIVITY, true);
+    job.getConfiguration().setInt(TableRecordReaderImpl.LOG_PER_ROW_COUNT, 100000);
+  }
 }
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/TableRecordReaderImpl.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/TableRecordReaderImpl.java
index 641f363a2c2..a21f4e07082 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/TableRecordReaderImpl.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/mapreduce/TableRecordReaderImpl.java
@@ -52,7 +52,7 @@ public class TableRecordReaderImpl {
   public static final String LOG_PER_ROW_COUNT
     = "hbase.mapreduce.log.scanner.rowcount";
 
-  static final Log LOG = LogFactory.getLog(TableRecordReader.class);
+  static final Log LOG = LogFactory.getLog(TableRecordReaderImpl.class);
 
   // HBASE_COUNTER_GROUP_NAME is the name of mapreduce counter group for HBase
   private static final String HBASE_COUNTER_GROUP_NAME =
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java
index 1af14ace480..25e3657be81 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java
@@ -3016,6 +3016,7 @@ public class HRegionServer implements ClientProtos.ClientService.BlockingInterfa
         if (request.hasScannerId()) {
           rsh = scanners.get(scannerName);
           if (rsh == null) {
+            LOG.info("Client tried to access missing scanner " + scannerName);
             throw new UnknownScannerException(
               "Name: " + scannerName + ", already closed?");
           }