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https://issues.apache.org/jira/browse/HADOOP-6616?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13471805#comment-13471805
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Joep Rottinghuis commented on HADOOP-6616:
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Update looks good. I ran the perl and python example scripts. The first two ran
fine. See comment below on the BASH script.
Nit: (line 18 of the patch)
The <code>NameNode</code> and the <code>JobTracker</code> obtains
NN and JT obtain (singular).
I think this same error already exists in
http://hadoop.apache.org/docs/r1.0.3/cluster_setup.html#Hadoop+Rack+Awareness
One refinement to
{noformat}
The jobtracker uses rack awareness to reduce network transfers of HDFS data
blocks, as it will schedule tasks on nodes located within the same rack
containing the needed HDFS data blocks.
{noformat}
If the tasks cannot be scheduled on the DNs containing the needed HDFS blocks,
then the tasks will be scheduled on the same rack to reduce network transfers
if possible.
Line 41 again the NN and JT obtain instead of obtains (plural).
Line 65:
{noformat}
Hadoop will send multiple IP addresses on STDIN when forking the topology
script.
{noformat}
I think IP addresses are passed as arguments, not on STDIN. The first Perl
script reads this correctly from ARGV but the comment in the script reads that
it gets it from STDIN.
The BASH example for flat network always returns /rack-unkown
I think that is due to
{noformat}
if [ -n $# ];
{noformat}
Something like
{noformat}
if [ "$1" == "" ]; then
{noformat}
Once that is fixed, the script errors out missing closing brace in the for
statement. This should be:
{noformat}
for host in ${BASH_ARGV[*]}; do
{noformat}
I had some trouble with mis-matching single quote (which is strange as they
occurred only in the comments).
Same STDIN comment in other scripts.
I could not get the last python script (the one that makes assumptions about
the physical environment) to work because I do not have hosts that are called
"dn" something.
> Improve documentation for rack awareness
> ----------------------------------------
>
> Key: HADOOP-6616
> URL: https://issues.apache.org/jira/browse/HADOOP-6616
> Project: Hadoop Common
> Issue Type: Improvement
> Components: documentation
> Reporter: Jeff Hammerbacher
> Labels: newbie
> Attachments: hadoop-6616.patch, hadoop-6616.patch.2
>
>
> The current documentation for rack awareness
> (http://hadoop.apache.org/common/docs/r0.20.0/cluster_setup.html#Hadoop+Rack+Awareness)
> should be augmented to include a sample script.
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