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HDFS Xrootd Fallback Administration

Finding Files with a Given Replication

The examples here use the hadoop_lsr tool, which can be found on uaf at:

~jdost/bin/hadoop_lsr

List files of a given replication (2 in this example):

hadoop_lsr 2 /some/dir/in/hadoop

Find all files of replication 2 recursively in all subdirectories:

hadoop_lsr 2 -R /some/dir/in/hadoop

ALERT! NOTE the -R option can cause a load increase on the namenode if the file namespace is large enough, use with care!

Changing File Replication

These examples only require built-in hadoop commands.

ALERT! NOTE you need to either be the cmswriter user to modify replication or have root access on a node with a hadoop client.

Set replication to 1 for a single file:

hadoop fs -setrep 1 /some/file/in/hadoop

Set replication to 1 recursively for all files in a directory and all its subdirectories:

hadoop fs -setrep -R 1 /some/dir/in/hadoop

ALERT! NOTE the -R option can cause a load increase on the namenode if the file namespace is large enough, use with care!

Using a bash for loop to set replication to 1 over a list of directories in a file called rep1.txt:

while read line;do echo `date +%T` $line;hadoop fs -setrep -R 1 $line > /dev/null;done < rep1.txt

Namespaces with Replication Set to 1

As of 2014-03-27 we have Replication reduced to 1 for the following:

  • /cms/phedex/store/data/Run2012D/

2014-08-04:

  • /cms/phedex/store/himc
  • /cms/phedex/store/data/Run2012A
  • /cms/phedex/store/data/Run2012B
  • /cms/phedex/store/data/Run2012C
  • /cms/phedex/store/data/Fall13
  • /cms/phedex/store/data/Summer13
  • /cms/phedex/store/relval
  • /cms/phedex/store/mc/Summer12_DR53X

Monitoring Fallback

Currently the best place to check to ensure fallback is working as expected is the udp log at xrootd-proxy.t2.ucsd.edu:

/var/log/xrootd/hdfs-mon-snatcher.log

This section will be updated once more monitoring tools are developed.

-- JeffreyDost - 2014/03/27

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Topic revision: r3 - 2014/08/04 - 20:18:57 - JeffreyDost
 
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