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copied!<p>i don't know if I have correctly understood your question but here's some informations : </p> <p><strong>Setting permissions on local filesystem</strong></p> <p>Setting permissions is clearly realevant and needed. Indeed, this permissions can enforce your cluster security by preventing non user or even non owner from modify your data. Even if you will probably use lower security to set up your cluster, after its intallation you can modify them to have a safe use.</p> <p>By the way setting your permission to 777 is almost never a good solution, even if it does not imply direct troubles.<br> [EDIT] : The good behavior is trying to set as less rights as possible. So while Hadoop works, try to set lower access right (best will be 720). But I can not guarantee that hadoop works with other permissions than 755 as it is the default values.</p> <p><em>almost off-topic</em> </p> <hr> <p><strong>for CHMOD bits</strong><br> values are setted by : Owner User Others each of these values have 3 capabilities : Read Write Execute (in this order) Since theses capabilities can be setted to true(1) or false(0) it result on an octal value given by the binary values. </p> <p>For instance<br> for Owner you want all right, so rwx => 111 = 4 + 2 + 1 = 7<br> for User only read and execute, r-x => 101 = 4+0+1 = 5<br> and same for others, r-x => 101 = 4+0+1 = 5</p> <p>So you have to do a chmod 755 file</p> <p><strong>for hdfs rights on host filesystem</strong> </p> <p>Hadoop is very sensitive to files and directories access rights on its file system. So if you have not setted them correctly it can throw exception and even prevent namenode or datanodes from starting.<br> As far as i know some parts of your files have to be own by hadoop:hadoop or hdfs:hadoop and some others by mapred:hadoop (according to your hdfs and mapred users and groups).</p> <hr>

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