:original_name: mrs_01_0791.html

.. _mrs_01_0791:

Configuring Memory Management
=============================

Scenario
--------

In HDFS, each file object needs to register corresponding information in the NameNode and occupies certain storage space. As the number of files increases, if the original memory space cannot store the corresponding information, you need to change the memory size.

Configuration Description
-------------------------

**Navigation path for setting parameters:**

Go to the **All Configurations** page of HDFS by referring to :ref:`Modifying Cluster Service Configuration Parameters <mrs_01_2125>`.

.. table:: **Table 1** Parameter description

    
   | Parameter             | Description                                                                                                                                                                                                                                            | Default Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
    
   | GC_PROFILE            | The NameNode memory size depends on the size of FsImage, which can be calculated based on the following formula: FsImage size = Number of files x 900 bytes. You can estimate the memory size of the NameNode of HDFS based on the calculation result. | custom                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
   |                       |                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       | The value range of this parameter is as follows:                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       |                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       | -  **high**: 4 GB                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       | -  **medium**: 2 GB                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       | -  **low**: 256 MB                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       | -  **custom**: The memory size can be set according to the data size in GC_OPTS.                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
    
   | GC_OPTS               | JVM parameter used for garbage collection (GC). This parameter is valid only when **GC_PROFILE** is set to **custom**. Ensure that the **GC_OPT** parameter is set correctly. Otherwise, the process will fail to be started.                          | -Xms2G -Xmx4G -XX:NewSize=128M -XX:MaxNewSize=256M -XX:MetaspaceSize=128M -XX:MaxMetaspaceSize=128M -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:CMSInitiatingOccupancyFraction=65 -XX:+PrintGCDetails -Dsun.rmi.dgc.client.gcInterval=0x7FFFFFFFFFFFFFE -Dsun.rmi.dgc.server.gcInterval=0x7FFFFFFFFFFFFFE -XX:-OmitStackTraceInFastThrow -XX:+PrintGCDateStamps -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10 -XX:GCLogFileSize=1M -Djdk.tls.ephemeralDHKeySize=2048 |
   |                       |                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       | .. important::                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       |                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       |    NOTICE:                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
   |                       |    Exercise caution when you modify the configuration. If the configuration is incorrect, the services are unavailable.                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
    
