diff --git a/core/src/main/scala/org/apache/spark/shuffle/sort/SortShuffleWriter.scala b/core/src/main/scala/org/apache/spark/shuffle/sort/SortShuffleWriter.scala
index 9a356d0dbaf17..24db2f287a47b 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/sort/SortShuffleWriter.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/sort/SortShuffleWriter.scala
@@ -40,7 +40,7 @@ private[spark] class SortShuffleWriter[K, V, C](
   private val ser = Serializer.getSerializer(dep.serializer.orNull)
 
   private val conf = SparkEnv.get.conf
-  private val fileBufferSize = conf.getInt("spark.shuffle.file.buffer.kb", 100) * 1024
+  private val fileBufferSize = conf.getInt("spark.shuffle.file.buffer.kb", 32) * 1024
 
   private var sorter: ExternalSorter[K, V, _] = null
   private var outputFile: File = null
diff --git a/core/src/main/scala/org/apache/spark/storage/ShuffleBlockManager.scala b/core/src/main/scala/org/apache/spark/storage/ShuffleBlockManager.scala
index 28aa35bc7e147..f9fdffae8bd8f 100644
--- a/core/src/main/scala/org/apache/spark/storage/ShuffleBlockManager.scala
+++ b/core/src/main/scala/org/apache/spark/storage/ShuffleBlockManager.scala
@@ -73,7 +73,7 @@ class ShuffleBlockManager(blockManager: BlockManager) extends Logging {
   val sortBasedShuffle =
     conf.get("spark.shuffle.manager", "") == classOf[SortShuffleManager].getName
 
-  private val bufferSize = conf.getInt("spark.shuffle.file.buffer.kb", 100) * 1024
+  private val bufferSize = conf.getInt("spark.shuffle.file.buffer.kb", 32) * 1024
 
   /**
    * Contains all the state related to a particular shuffle. This includes a pool of unused
diff --git a/core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala b/core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala
index 5d10a1f84493c..4178dbde65ef9 100644
--- a/core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala
+++ b/core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala
@@ -107,7 +107,7 @@ class ExternalAppendOnlyMap[K, V, C](
   private var _memoryBytesSpilled = 0L
   private var _diskBytesSpilled = 0L
 
-  private val fileBufferSize = sparkConf.getInt("spark.shuffle.file.buffer.kb", 100) * 1024
+  private val fileBufferSize = sparkConf.getInt("spark.shuffle.file.buffer.kb", 32) * 1024
   private val keyComparator = new HashComparator[K]
   private val ser = serializer.newInstance()
 
diff --git a/core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala b/core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala
index b04c50bd3e196..b5a847c6b49c0 100644
--- a/core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala
+++ b/core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala
@@ -83,7 +83,7 @@ private[spark] class ExternalSorter[K, V, C](
 
   private val conf = SparkEnv.get.conf
   private val spillingEnabled = conf.getBoolean("spark.shuffle.spill", true)
-  private val fileBufferSize = conf.getInt("spark.shuffle.file.buffer.kb", 100) * 1024
+  private val fileBufferSize = conf.getInt("spark.shuffle.file.buffer.kb", 32) * 1024
 
   // Size of object batches when reading/writing from serializers.
   //
diff --git a/docs/configuration.md b/docs/configuration.md
index 870343f1c0bd2..2b202bcd77c1b 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -258,7 +258,7 @@ Apart from these, the following properties are also available, and may be useful
 </tr>
 <tr>
   <td><code>spark.shuffle.file.buffer.kb</code></td>
-  <td>100</td>
+  <td>32</td>
   <td>
     Size of the in-memory buffer for each shuffle file output stream, in kilobytes. These buffers
     reduce the number of disk seeks and system calls made in creating intermediate shuffle files.