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From Dheeren Bebortha <dbebor...@salesforce.com>
Subject RE: Support of RHEL version
Date Thu, 24 Jan 2013 17:46:33 GMT
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?
-Dheeren

-----Original Message-----
From: Alexander Alten-Lorenz [mailto:wget.null@gmail.com] 
Sent: Thursday, January 24, 2013 9:41 AM
To: cdh-user@cloudera.org
Subject: Re: Support of RHEL version

Hi,

Moving the post to cdh-user@cloudera.org
(https://groups.google.com/a/cloudera.org/forum/?fromgroups=#!forum/cdh-user)
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.

Cheers,
 Alex

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
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
http://mapredit.blogspot.com
German Hadoop LinkedIn Group: http://goo.gl/N8pCF


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