MapReduce vs hosts (Cannot resolve the host name)

[Jean-Marc Spaggiari <je...@spaggiari.org>]

Hi,

I'm facing a small issue, most probably configuration related, that
I'm not able to solve.

I'm trying to run the rowcounter.

Here is the command line:
export HADOOP_HOME=/home/hadoop/hadoop-1.0.3/; export
HBASE_HOME=/home/hbase/hbase-0.94.0/;
HADOOP_CLASSPATH=`${HBASE_HOME}/bin/hbase classpath`
${HADOOP_HOME}/bin/hadoop jar ${HBASE_HOME}/hbase-0.94.0.jar
rowcounter work_proposed -Dhbase.client.scanner.cachi=10

I'm getting errors for each of my regions:
12/10/11 09:10:45 ERROR mapreduce.TableInputFormatBase: Cannot resolve
the host name for /192.168.23.9 because of
javax.naming.NameNotFoundException: DNS name not found [response code
3]; remaining name '9.23.168.192.in-addr.arpa'

I have 25 regions for this table, so I have 25 lines like that.

And then it's blocking at:
12/10/11 09:10:45 INFO mapred.JobClient: Running job: job_201209151131_0005
12/10/11 09:10:46 INFO mapred.JobClient:  map 0% reduce 0%

Here is an extract of my host file:
192.168.23.9    node5
192.168.23.8    node4
192.168.23.7    node3
192.168.23.6    node2
192.168.23.5    node1

Hadoop is working fine.
HBase is working fine.

If I try the shell and do a count, it's working fine.

If I try with bin/hbase org.apache.hadoop.hbase.mapreduce.RowCounter
work_proposed it's working fine, but it's doing the regions one by
one, and not in parallel. So it's very slow.

I can ping the nodes, by name or IPs, I can ssh them too.

Any idea where I can start to look at?

Thanks,

JM

Re: MapReduce vs hosts (Cannot resolve the host name)

[Jean-Marc Spaggiari <je...@spaggiari.org>]

Oh, this is archeology! ;) Almost 2 years old post ;)

I have not solved this.

It doesn't create any issue. I think you should consider is as a warning
more than as an error. It is most probably due to some DNS vs Reverse DNS
results.

JM

2014-09-23 23:50 GMT-04:00 Om Parkash <mr...@gmail.com>:

> Hi Jean-Marc
>       I have same problem if you found any solution please tell.
>
>
>
> --
> View this message in context:
> http://apache-hbase.679495.n3.nabble.com/MapReduce-vs-hosts-Cannot-resolve-the-host-name-tp4032838p4064321.html
> Sent from the HBase User mailing list archive at Nabble.com.
>

Re: MapReduce vs hosts (Cannot resolve the host name)

[Om Parkash <mr...@gmail.com>]

Hi Jean-Marc
      I have same problem if you found any solution please tell.



--
View this message in context: http://apache-hbase.679495.n3.nabble.com/MapReduce-vs-hosts-Cannot-resolve-the-host-name-tp4032838p4064321.html
Sent from the HBase User mailing list archive at Nabble.com.

Re: MapReduce vs hosts (Cannot resolve the host name)

[Jean-Marc Spaggiari <je...@spaggiari.org>]

Hi St.Ack,

Thanks for your reply.

Finally, seems that this is not blocking the application. It's stated
as "ERROR"s but it's still running after that. After some time, I'm
getting some results.

I don't have any DNS on my cluster. All servers have the same host
file and static IPs. Is it mandatory to have a DNS to run HBase? Or
can it run without?

JM

2012/10/11, Stack <st...@duboce.net>:
> On Thu, Oct 11, 2012 at 6:17 AM, Jean-Marc Spaggiari
> <je...@spaggiari.org> wrote:
>> Any idea where I can start to look at?
>>
>
> Sounds like DNS -- forward and reverse lookups -- work on the machine
> you are launching your job from but not out on your cluster.  Check
> DNS on the cluster members?
> St.Ack
>

Re: MapReduce vs hosts (Cannot resolve the host name)

[Stack <st...@duboce.net>]

On Thu, Oct 11, 2012 at 6:17 AM, Jean-Marc Spaggiari
<je...@spaggiari.org> wrote:
> Any idea where I can start to look at?
>

Sounds like DNS -- forward and reverse lookups -- work on the machine
you are launching your job from but not out on your cluster.  Check
DNS on the cluster members?
St.Ack