How To Solve Issues Related to Log – Unable to get a valid mac address; will use a dummy address

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Updated: Feb-20

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Troubleshooting background

To troubleshoot Elasticsearch log “Unable to get a valid mac address; will use a dummy address” it’s important to understand common problems related to Elasticsearch concepts: Index, Memory. See detailed explanations below complete with common problems, examples and useful tips.

Memory in Elasticsearch

What is it

Memory is one of the most critical resources to monitor in Elasticsearch. Elasticsearch runs on JVM and uses heap memory areas for query cache, request cache, accessing lucene segments and storing fielddata for aggregations and sorting.

Commos problems and important points
  • The most common error that arises in Elasticsearch is OutOfMemory error. This error comes when the node is not able to cope up with the required heap size space. To avoid this, you need to closely monitor the heap utilization and garbage collector performance.
  • As per the most up-to-date best practices you should not allocate more than 50 percent of total RAM to JVM heap size. Starting from Elasticsearch version 5.x onward this can be set using -Xms and -Xmx parameters inside jvm.options configuration file. The defaults are set to 1 GB for both minimum and maximum heap size.
  • The heap size should not set more than 31 GB in any case to avoid the poor garbage collection.


To help troubleshoot related issues we have gathered selected Q&A from the community and issues from Github , please review the following for further information :

1 T Able To Start Sonar Server  

2Ix Path Building Failed And Unable  


Log Context

Log ”Unable to get a valid mac address; will use a dummy address” classname is MacAddressProvider.java
We have extracted the following from Elasticsearch source code to get an in-depth context :

             logger.warn("Unable to get mac address; will use a dummy address"; t);
            // address will be set below
        }

        if (!isValidAddress(address)) {
            logger.warn("Unable to get a valid mac address; will use a dummy address");
            address = constructDummyMulticastAddress();
        }

        byte[] mungedBytes = new byte[6];
        SecureRandomHolder.INSTANCE.nextBytes(mungedBytes);






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