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From Alexander Alten-Lorenz <wget.n...@gmail.com>
Subject Re: Support of RHEL version
Date Thu, 24 Jan 2013 18:01:16 GMT
Do you mean Transparent Huge Page Defrag (https://bugzilla.redhat.com/show_bug.cgi?id=805593)?

Do echo never > /sys/kernel/mm/redhat_transparent_hugepage/defrag

- Alex

On Jan 24, 2013, at 6:46 PM, Dheeren Bebortha <dbebortha@salesforce.com> wrote:

> 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
>> ?<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

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

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