Cloudera Administrator Troubleshooting Guide
1. Introduction
This guide provides a comprehensive overview of common issues encountered in Cloudera's
Hadoop ecosystem, along with detailed troubleshooting steps. Effective troubleshooting is essential
to maintain the health and performance of your Cloudera cluster.
2. HDFS Troubleshooting
Handling Rollback Issues with Zero Downtime Upgrade (ZDU)
During a rollback of a failed Zero Downtime Upgrade (ZDU), issues may arise related to file
corruption due to block generation stamps. Steps include recovering files appended during ZDU,
recovering previous files Hsync'ed during ZDU, and handling open files in a corrupt state.
HeapDumpPath Issues
The HeapDumpPath (/tmp) in Hive nodes often gets full due to .hprof files generated when
processes exit with an Out Of Memory exception. To resolve this, modify the Tez Application Master
and Task Command Line Options to change the HeapDumpPath value.
3. YARN Troubleshooting
Managing Long-Running Applications
You can manage long-running YARN applications using the YARN Services API. Configure the API
to handle the life cycle of applications, including increasing or decreasing the number of application
instances.
Running YARN Services
Issues may arise when running services on YARN. Proper configuration and use of YARN Services
API can help in managing and troubleshooting these services.
4. Hive Troubleshooting
Issues with HeapDumpPath
To manage space issues caused by heap dumps, consider changing the default HeapDumpPath
from /tmp to a different location or disabling automatic heap dumps.
Query Failures
Hive queries may fail with 'Counters limit exceeded' errors. Increase the value for Tez counters and
counter groups to resolve this issue.
Managing High Partition Workloads
High partition workloads can cause execution errors. Proper configuration of HiveServer (HS2) and
Hive Metastore (HMS) services can prevent these errors.
HiveServer Unresponsiveness
Large queries running in parallel can cause HiveServer to become unresponsive. To prevent
blocking, disable the cache wait for pending results property.
5. Impala Troubleshooting
Data Migration Issues
When migrating Impala data to CDP, be aware of configuration changes and performance impacts.
Ensure that you set the correct warehouse directories and ACLs to avoid issues post-migration.
Impala Configuration Differences
Adjust configurations such as default file formats, use_local_catalog, and metadata management to
ensure optimal performance in the CDP environment.
Interoperability between Hive and Impala
Ensure that tables created in Hive are compatible with Impala by using appropriate file formats and
configurations to maintain interoperability.
6. Cloudera Data Warehouse Troubleshooting
Diagnostic Bundles
Diagnostic bundles can be collected and analyzed to troubleshoot issues within Cloudera Data
Warehouse environments. These bundles include logs and event histories crucial for diagnosing
problems.
Common Issues
Address common issues in Cloudera Data Warehouse environments by using diagnostic tools and
adhering to best practices in configuration management.
7. Conclusion
This guide has provided an overview of key troubleshooting steps for Cloudera components.
Regular monitoring and proactive updates are critical to maintaining the health and performance of
your Cloudera cluster.
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