Help Center/ MapReduce Service/ User Guide/ MRS Cluster O&M/ MRS Cluster Alarm Handling Reference/ ALM-14017 NameNode Direct Memory Usage Exceeds the Threshold
Updated on 2024-09-23 GMT+08:00
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ALM-14017 NameNode Direct Memory Usage Exceeds the Threshold

Description

The system checks the direct memory usage of the HDFS service every 30 seconds. This alarm is generated when the direct memory usage of a NameNode instance exceeds the threshold (90% of the maximum memory).

The alarm is cleared when the direct memory usage is less than the threshold.

Attribute

Alarm ID

Alarm Severity

Automatically Cleared

14017

Major

Yes

Parameters

Name

Meaning

Source

Specifies the cluster for which the alarm is generated.

ServiceName

Specifies the service for which the alarm is generated.

RoleName

Specifies the role for which the alarm is generated.

HostName

Specifies the host for which the alarm is generated.

Trigger Condition

Specifies the threshold triggering the alarm. If the current indicator value exceeds this threshold, the alarm is generated.

Impact on the System

If the available direct memory of the HDFS service is insufficient, a memory overflow occurs and the service breaks down.

Possible Causes

The direct memory of the NameNode instance is overused or the direct memory is inappropriately allocated.

Procedure

Check the direct memory usage.

  1. On the FusionInsight Manager portal, choose O&M > Alarm > Alarms. On the displayed interface, click the drop-down button of ALM-14017 NameNode Direct Memory Usage Exceeds the Threshold. Then check the role name in Location and confirm the IP adress of the instance.
  2. On the FusionInsight Manager portal, choose Cluster > Name of the desired cluster > Services > HDFS > Instance > NameNode (IP address for which the alarm is generated). Click the drop-down menu in the upper right corner of Chart, choose Customize > Resource, and select NameNode Memory to check the direct memory usage.
  3. Check whether the used direct memory of NameNode reaches 90% of the maximum direct memory specified for NameNode by default.

    • If yes, go to 4.
    • If no, go to 8.

  4. On the FusionInsight Manager portal, choose Cluster > Name of the desired cluster > Services > HDFS > Configurations > All Configurations > NameNode > System to check whether "-XX:MaxDirectMemorySize" exists in the GC_OPTS parameter.

    • If yes, go to 5.
    • If no, go to 6.

  5. In the GC_OPTS parameter, delete "-XX:MaxDirectMemorySize". Save the configuration and restart the NameNode instance.

    • During the restart of the active NameNode, a NameNode active/standby switchover occurs. As a result, no active node is available in the system for a short period of time (in the transition period of the active/standby switchover), and an alarm indicating that the HDFS service is unavailable may be generated. In addition, an error is reported during the running read and write tasks, but services are not interrupted.
    • Services are not affected after the standby NameNode is restarted.

  6. Check whether the ALM-14007 NameNode Heap Memory Usage Exceeds the Threshold exists.

    • If yes, handle the alarm by referring to ALM-14007 NameNode Heap Memory Usage Exceeds the Threshold.
    • If no, go to 7.

  7. Check whether the alarm is cleared.

    • If yes, no further action is required.
    • If no, go to 8.

Collect fault information.

  1. On the FusionInsight Manager portal, choose O&M > Log > Download.
  2. Select NameNode in the required cluster from the Service.
  3. Click in the upper right corner, and set Start Date and End Date for log collection to 10 minutes ahead of and after the alarm generation time, respectively. Then, click Download.
  4. Contact the O&M personnel and send the collected logs.

Alarm Clearing

After the fault is rectified, the system automatically clears this alarm.

Related Information

None