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From <Nilesh_Sang...@Dell.com>
Subject Support of RHEL version
Date Thu, 24 Jan 2013 17:28:59 GMT
Hi,

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?

-Nilesh


https://ccp.cloudera.com/display/CDH4DOC/Known+Issues+and+Work+Arounds+in+CDH4


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.
Bug: https://bugzilla.redhat.com/show_bug.cgi?id=805593
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:
?<https://ccp.cloudera.com/display/CDH4DOC/Known+Issues+and+Work+Arounds+in+CDH4>
echo never > /sys/kernel/mm/redhat_transparent_hugepage/defrag



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