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RE: Support of RHEL version
I do not think this is a cdh specific issues. If this is a hbase compaction issue it would be all pervading as long as it si RHEL62 and above!
Am I reading it right?

-----Original Message-----
From: Alexander Alten-Lorenz [mailto:[EMAIL PROTECTED]]
Sent: Thursday, January 24, 2013 9:41 AM
Subject: Re: Support of RHEL version


Moving the post to [EMAIL PROTECTED]
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 below.

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


On Jan 24, 2013, at 6:28 PM, <[EMAIL PROTECTED]> 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 compaction:
> ?<https://ccp.cloudera.com/display/CDH4DOC/Known+Issues+and+Work+Aroun
> ds+in+CDH4> echo never >
> /sys/kernel/mm/redhat_transparent_hugepage/defrag

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