Using Hadoop distcp to load data into Riak-CS

Sajner, Daniel G dsajner at cas.org
Wed Jul 10 08:20:46 EDT 2013


Hi.

Sorry about the "fake sender" in the subject of the original message.  Our mail security system is funny like that...

Anyhow, we discovered that distcp puts a temp file name in place and then tries to do a PUT (copy) that copy the file to the permanent name.  From the documentation that doesn't appear to be supported by Riak. http://docs.basho.com/riakcs/latest/references/apis/storage/RiakCS-PUT-Object-Copy/

I still would like to hear if anyone else has had success with distcp.  Maybe there is another version out there that works differently.

Thanks,
Dan


From: riak-users [mailto:riak-users-bounces at lists.basho.com] On Behalf Of Sajner, Daniel G
Sent: Tuesday, July 09, 2013 7:56 AM
To: 'riak-users at lists.basho.com'
Subject: [PMX:FAKE_SENDER] Using Hadoop distcp to load data into Riak-CS

Hi.

I'm trying to load data from a Hadoop cluster using distcp.  Distcp supports the S3 API, but I'm running into issues.
Has anyone tested/had success with this process?  Any help is appreciated!  Details below...

Thanks,
Dan


Here's my setup:
Hadoop cluster with a small text file in hdfs.
Jets3t.properties file configured to use a proxy host.
Proxy host running Varnish basically to serve as a load balancer at this point.  All caching is currently disabled.
Riak-CS/Riak running on a 6 server cluster.

Here's the scenario:
I'm running this command...


Ø  hadoop distcp -libjars ./jets3t-config.jar hdfs://hadoop.node.address/user/dan/test.txt s3n://riak-user-key:riak-secret@testing/

I see many requests and responses in the varnishlog so I know communication is succeeding.  The distcp process throws an exception and I see empty files and directories left on my Riak system.

The exception looks like this:

13/07/08 15:52:42 INFO tools.DistCp: sourcePathsCount=1
13/07/08 15:52:42 INFO tools.DistCp: filesToCopyCount=1
13/07/08 15:52:42 INFO tools.DistCp: bytesToCopyCount=93.0
13/07/08 15:52:42 INFO mapred.JobClient: Running job: job_201307031542_0023
13/07/08 15:52:43 INFO mapred.JobClient:  map 0% reduce 0%
13/07/08 15:52:50 INFO mapred.JobClient: Job complete: job_201307031542_0023
13/07/08 15:52:50 INFO mapred.JobClient: Counters: 6
13/07/08 15:52:50 INFO mapred.JobClient:   Job Counters
13/07/08 15:52:50 INFO mapred.JobClient:     SLOTS_MILLIS_MAPS=6980
13/07/08 15:52:50 INFO mapred.JobClient:     Total time spent by all reduces waiting after reserving slots (ms)=0
13/07/08 15:52:50 INFO mapred.JobClient:     Total time spent by all maps waiting after reserving slots (ms)=0
13/07/08 15:52:50 INFO mapred.JobClient:     Launched map tasks=1
13/07/08 15:52:50 INFO mapred.JobClient:     SLOTS_MILLIS_REDUCES=0
13/07/08 15:52:50 INFO mapred.JobClient:     Failed map tasks=1
13/07/08 15:52:50 INFO mapred.JobClient: Job Failed: NA
With failures, global counters are inaccurate; consider running with -i
Copy failed: java.io.IOException: Job failed!
        at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1246)
        at org.apache.hadoop.tools.DistCp.copy(DistCp.java:667)
        at org.apache.hadoop.tools.DistCp.run(DistCp.java:881)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
        at org.apache.hadoop.tools.DistCp.main(DistCp.java:908)


And Riak is left like this:

Ø  s3cmd ls s3://testing
                       DIR   s3://testing/_distcp_logs_7bhq3z/
                       DIR   s3://testing/_distcp_logs_j9re3f/
2013-07-09 03:54         0   s3://testing/_distcp_logs_7bhq3z_$folder$
2013-07-09 00:03         0   s3://testing/_distcp_logs_j9re3f_$folder$
2013-07-08 19:52         0   s3://testing/test.txt


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