We are working on implementing Cloudera distributed Hadoop (CDH 4.x) on our environment. Cloudera website talks about supporting RHEL 6.1 version with challenges/issues with the newer version. It also though provides a workaround for it. Wanted to hear from the community on the supported versions of RedHat Linux and any guidance on which version to choose?
Red Hat Linux (RHEL 6.2 and 6.3)
- Poor performance running Hadoop on RHEL 6.2 or later when transparent hugepage compaction is enabled
RHEL 6.2 and 6.3 include a feature called "transparent hugepage compaction" which interacts poorly with Hadoop workloads. This can cause a serious performance regression compared to other operating system versions on the same hardware.
Symptom: top and other system monitoring tools show a large percentage of the CPU usage classified as "system CPU". If system CPU usage is 30% or more of the total CPU usage, your system may be experiencing this issue.
Severity: Medium (up to 3x performance loss)
Anticipated Resolution: Currently working with Red Hat to resolve for a future RHEL update
Workaround: Add the following command to /etc/rc.local to disable transparent hugepage compaction:
echo never > /sys/kernel/mm/redhat_transparent_hugepage/defrag