[HDFS-12555] HDFS federation should support configure secondary directory

• Type: Improvement
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: 3.0.0
• Component/s: federation

Environment

2.6.0-cdh5.10.0

• Target Version/s: 3.0.0
• Hadoop Flags: Reviewed
• Assignee: luoge123
• Reporter: luoge123
• Created: 27/Sep/17 03:12
• Updated: 19/Dec/17 18:48

Description

HDFS federation support multiple namenodes horizontally scales the file system namespace. As the amount of data grows, using a single group of namenodes to manage a single directory, namenode still achieves performance bottlenecks. In order to reduce the pressure of namenode, we can split out the secondary directory, and manager it by a new namenode. This is transparent for users.
For example, nn1 only manager the /user directory, when nn1 achieve performance bottlenecks, we can split out /user/hive directory, and ues nn2 to manager it.
That means core-site.xml should support as follows configuration.

<property>
<name>fs.viewfs.mounttable.nsX.link./user</name>
<value>hdfs://nn1:8020/user</value>
</property>

<property>
<name>fs.viewfs.mounttable.nsX.link./user/hive</name>
<value>hdfs://nn2:8020/user/hive</value>
</property>