Hey John, Sorta unclear on what is prompting this question (to answer it more specifically) but my response below:
On Tue, Apr 9, 2013 at 9:05 AM, John Meza <[email protected]> wrote: > The default mode for hadoop is Standalone, PsuedoDistributed and Fully > Distributed modes. It is configured for Psuedo and Fully Distributed via > configuration file, but defaults to Standalone otherwise (correct?). The mapred-default.xml we ship, has "mapred.job.tracker" (0.20.x/1.x/0.22.x) set to local, or "mapreduce.framework.name" (0.23.x, 2.x, trunk) set to local. This is why, without reconfiguring an installation to point to a proper cluster (JT or YARN), you will get local job runner activated. > Question about the -defaulting- mechanism: > -Does it get the -default- configuration via one of the config files? For any Configuration type of invocation: 1. First level of defaults come from *-default.xml embedded inside the various relevant jar files. 2. Configurations further found in a classpath resource XML (core,mapred,hdfs,yarn, *-site.xmls) are applied on top of the defaults. 3. User applications' code may then override this set, with any settings of their own, if needed. > -Or does it get the -default- configuration via hard-coded values? There may be a few cases of hardcodes, missing documentation and presence in *-default.xml, but they should still be configurable via (2) and (3). > -Or another mechanism? -- Harsh J
