diff --git a/mongodb/README.md b/mongodb/README.md
index 1fed1348e4c172e1a2b3abd27a914eb43ecbffe4..dd139c42c6c157cb360e4d6b47c6e55edb8711b7 100644
--- a/mongodb/README.md
+++ b/mongodb/README.md
@@ -39,7 +39,7 @@ See the next section for the list of configuration parameters for MongoDB.
 
 ### `mongodb.database` (default: `ycsb`)
 
-### `mongodb.writeConcern` (default `safe`)
+### `mongodb.writeConcern` (default `acknowledged`, options are `errors_ignored`, `unacknowledged`, `acknowledged`, `journaled`, `replica_acknowledged`)
 
 ### `mongodb.maxconnections` (default `10`)
 
diff --git a/mongodb/src/main/java/com/yahoo/ycsb/db/AsyncMongoDbClient.java b/mongodb/src/main/java/com/yahoo/ycsb/db/AsyncMongoDbClient.java
index 645b233ed320edbf9b85e4310394b25280c6b83e..d83fd43eca6077aeb1c21a1ab456744059c38a37 100644
--- a/mongodb/src/main/java/com/yahoo/ycsb/db/AsyncMongoDbClient.java
+++ b/mongodb/src/main/java/com/yahoo/ycsb/db/AsyncMongoDbClient.java
@@ -145,32 +145,31 @@ public class AsyncMongoDbClient extends DB {
             String url = props.getProperty("mongodb.url",
                     "mongodb://localhost:27017");
             database = props.getProperty("mongodb.database", "ycsb");
-            final String writeConcernType = props.getProperty(
-                    "mongodb.writeConcern",
-                    props.getProperty("mongodb.durability", "safe"))
+            String writeConcernType = props.getProperty("mongodb.writeConcern",
+                    props.getProperty("mongodb.durability", "acknowledged"))
                     .toLowerCase();
 
-            if ("none".equals(writeConcernType)) {
+            if ("errors_ignored".equals(writeConcernType)) {
                 writeConcern = Durability.NONE;
             }
-            else if ("safe".equals(writeConcernType)) {
-                writeConcern = Durability.ACK;
+            else if ("unacknowledged".equals(writeConcernType)) {
+                writeConcern = Durability.NONE;
             }
-            else if ("normal".equals(writeConcernType)) {
+            else if ("acknowledged".equals(writeConcernType)) {
                 writeConcern = Durability.ACK;
             }
-            else if ("fsync_safe".equals(writeConcernType)) {
-                writeConcern = Durability.fsyncDurable(10000);
+            else if ("journaled".equals(writeConcernType)) {
+                writeConcern = Durability.journalDurable(0);
             }
-            else if ("replicas_safe".equals(writeConcernType)) {
-                writeConcern = Durability.replicaDurable(10000);
+            else if ("replica_acknowledged".equals(writeConcernType)) {
+                writeConcern = Durability.replicaDurable(2, 0);
             }
             else {
                 System.err
-                        .println("ERROR: Invalid durability: '"
+                        .println("ERROR: Invalid writeConcern: '"
                                 + writeConcernType
                                 + "'. "
-                                + "Must be [ none | safe | normal | fsync_safe | replicas_safe ]");
+                                + "Must be [ errors_ignored | unacknowledged | acknowledged | journaled | replica_acknowledged ]");
                 System.exit(1);
             }
 
diff --git a/mongodb/src/main/java/com/yahoo/ycsb/db/MongoDbClient.java b/mongodb/src/main/java/com/yahoo/ycsb/db/MongoDbClient.java
index 792c0418e8ef35cd6cc623ef2702a55009aa0c99..814eb46ef1abb3600338d2ae9ec563236c9a3c64 100644
--- a/mongodb/src/main/java/com/yahoo/ycsb/db/MongoDbClient.java
+++ b/mongodb/src/main/java/com/yahoo/ycsb/db/MongoDbClient.java
@@ -39,7 +39,7 @@ import com.yahoo.ycsb.DBException;
  * Properties to set:
  * 
  * mongodb.url=mongodb://localhost:27017 mongodb.database=ycsb
- * mongodb.writeConcern=normal
+ * mongodb.writeConcern=acknowledged
  * 
  * @author ypai
  */
@@ -90,7 +90,9 @@ public class MongoDbClient extends DB {
 
             database = props.getProperty("mongodb.database", "ycsb");
             String writeConcernType = props.getProperty("mongodb.writeConcern",
-                    "safe").toLowerCase();
+                    "acknowledged").toLowerCase();
+
+            // Set connectionpool to size of ycsb thread pool
             final String maxConnections = props.getProperty(
                     "mongodb.maxconnections", "10");
             final String threadsAllowedToBlockForConnectionMultiplier = props
@@ -98,27 +100,27 @@ public class MongoDbClient extends DB {
                             "mongodb.threadsAllowedToBlockForConnectionMultiplier",
                             "5");
 
-            if ("none".equals(writeConcernType)) {
-                writeConcern = WriteConcern.NONE;
+            if ("errors_ignored".equals(writeConcernType)) {
+                writeConcern = WriteConcern.ERRORS_IGNORED;
             }
-            else if ("safe".equals(writeConcernType)) {
-                writeConcern = WriteConcern.SAFE;
+            else if ("unacknowledged".equals(writeConcernType)) {
+                writeConcern = WriteConcern.UNACKNOWLEDGED;
             }
-            else if ("normal".equals(writeConcernType)) {
-                writeConcern = WriteConcern.NORMAL;
+            else if ("acknowledged".equals(writeConcernType)) {
+                writeConcern = WriteConcern.ACKNOWLEDGED;
             }
-            else if ("fsync_safe".equals(writeConcernType)) {
-                writeConcern = WriteConcern.FSYNC_SAFE;
+            else if ("journaled".equals(writeConcernType)) {
+                writeConcern = WriteConcern.JOURNALED;
             }
-            else if ("replicas_safe".equals(writeConcernType)) {
-                writeConcern = WriteConcern.REPLICAS_SAFE;
+            else if ("replica_acknowledged".equals(writeConcernType)) {
+                writeConcern = WriteConcern.REPLICA_ACKNOWLEDGED;
             }
             else {
                 System.err
                         .println("ERROR: Invalid writeConcern: '"
                                 + writeConcernType
                                 + "'. "
-                                + "Must be [ none | safe | normal | fsync_safe | replicas_safe ]");
+                                + "Must be [ errors_ignored | unacknowledged | acknowledged | journaled | replica_acknowledged ]");
                 System.exit(1);
             }