我已经在core-site.xml配置文件中配置了net.topology.node.switch.mapping.impl。并把jar包放在了/opt/modules/hadoop-2.7.2/share/hadoop/common/lib目录。启动后出现如下错误。hadoop哪个目录可以启动时加载jar包呢？

java.lang.RuntimeException: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class >com.learning.rackawareness.RackAwareness not found
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2227)
    at org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager.<init>(DatanodeManager.java:208)
    at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.<init>(BlockManager.java:268)
    at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:737)
    at org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode.initialize(SecondaryNameNode.java:246)
    at org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode.<init>(SecondaryNameNode.java:192)
    at org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode.main(SecondaryNameNode.java:671)
Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class >com.learning.rackawareness.RackAwareness not found
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2195)
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2219)
    ... 6 more
Caused by: java.lang.ClassNotFoundException: Class >com.learning.rackawareness.RackAwareness not found
    at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2101)
    at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2193)
    ... 7 more
2019-10-07 15:23:41,958 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Stopping services started for active state
2019-10-07 15:23:41,970 INFO org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode: SHUTDOWN_MSG: