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From Alexander Alten-Lorenz <wget.n...@gmail.com>
Subject Re: Support of RHEL version
Date Thu, 24 Jan 2013 17:40:35 GMT

Moving the post to cdh-user@cloudera.org 
as it is CDH4 you specifically are asking about. BCC'd user@hadoop
lists, lets carry forward the discussion on the CDH lists. My response

RHEL 5.x and 6.x wil be supported. Means, RHEL 6.3 too.


On Jan 24, 2013, at 6:28 PM, <Nilesh_Sangani@Dell.com> wrote:

> 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
> ?<https://ccp.cloudera.com/display/CDH4DOC/Known+Issues+and+Work+Arounds+in+CDH4>
> echo never > /sys/kernel/mm/redhat_transparent_hugepage/defrag

Alexander Alten-Lorenz
German Hadoop LinkedIn Group: http://goo.gl/N8pCF

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