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From Prashant Sharma <prashan...@imaginea.com>
Subject Re: Why $HADOOP_PREFIX ?
Date Thu, 02 Feb 2012 00:54:41 GMT
@Harsh, I sometimes get similar thoughts :P. But wonder if there is
something can be done.

@Bobby, Thanks for elaborating the strange reason. :)

@Praveenesh, Yes, you can do away with sourcing of hadoop-config.sh and set
all the necessary variables by hand.


On Wed, Feb 1, 2012 at 10:38 PM, Harsh J <harsh@cloudera.com> wrote:

> Personal opinion here: For branch-1, I do think the earlier tarball
> structure was better. I do not see why it had to change for this
> version at least. Possibly was changed during all the work of adding
> packaging-related scripts for rpm/deb into Hadoop itself, but the
> tarball right now is not as usable as was before, and the older format
> would've still worked today.
>
> On Wed, Feb 1, 2012 at 10:31 PM, Robert Evans <evans@yahoo-inc.com> wrote:
> > I think it comes down to a long history of splitting and then remerging
> the hadoop project.  I could be wrong about a lot of this so take it worth
> a grain of salt.  Hadoop originally, and still is on 1.0 a single project.
>  HDFS, mapreduce and common are all compiled together into a single jar
> hadoop-core.  In that respect HADOOP_HOME made a lot of since because it
> was a single thing, with some dependencies that needed to be found by some
> shell scripts.
> >
> > Fast forward the projects were split, HADOOP_HOME was deprecated, and
> HADOOP_COMMON_HOME, HADOOP_MAPRED_HOME, and HADOOP_HDFS_HOME were born.
>  But if we install them all into a single tree it is a pain to configure
> all of these to point to the same place, but HADOOP_HOME is deprecated, so
> HADOOP_PREFIX was born.  NOTE: like was stated before all of these are
> supposed to be hidden from the end user and are intended more towards
> packaging and deploying hadoop.  Also the process is not done and it is
> likely to change further.
> >
> > --Bobby Evans
> >
> > On 2/1/12 8:10 AM, "praveenesh kumar" <praveenesh@gmail.com> wrote:
> >
> > Interesting and strange.
> > but are there any reason for setting $HADOOP_HOME to $HADOOP_PREFIX in
> > hadoop-conf.sh
> > and then checking in /bin/hadoop.sh whether $HADOOP_HOME is not equal to
> ""
> >
> > I mean if I comment out the export HADOOP_HOME=${HADOOP_PREFIX} in
> > hadoop-conf.sh, does it make any difference ?
> >
> > Thanks,
> > Praveenesh
> >
> > On Wed, Feb 1, 2012 at 6:04 PM, Prashant Sharma <prashant.s@imaginea.com
> >wrote:
> >
> >> I think you have misunderstood something. AFAIK or understand  these
> >> variables are set automatically when you run a script. it's name is
> obscure
> >> for some strange reason. ;).
> >>
> >> Warning: $HADOOP_HOME is deprecated is always there. whether the
> variable
> >> is set or not. Why?
> >> Because the hadoop-config is sourced in all scripts. And all it does is
> >> sets HADOOP_PREFIX as HADOOP_HOME. I think this can be reported as a
> bug.
> >>
> >> -P
> >>
> >>
> >> On Wed, Feb 1, 2012 at 5:46 PM, praveenesh kumar <praveenesh@gmail.com
> >> >wrote:
> >>
> >> > Does anyone have idea on Why $HADOOP_PREFIX was introduced instead of
> >> > $HADOOP_HOME in hadoop 0.20.205 ?
> >> >
> >> > I believe $HADOOP_HOME was not giving any troubles or is there a
> >> reason/new
> >> > feature that require $HADOOP_PREFIX to be added ?
> >> >
> >> > Its a kind of funny, but I got habitual of using $HADOOP_HOME. Just
> >> curious
> >> > to know for this change.
> >> > Also, there are some old packages ( I am not referring
> apache/cloudera/or
> >> > any hadoop distribution ), that depends on hadoop that still uses
> >> > $HADOOP_HOME inside. So its kind of weird when you use those packages,
> >> you
> >> > still get warning messages even though its suppressed from Hadoop
> side.
> >> >
> >> >
> >> > Thanks,
> >> > Praveenesh
> >> >
> >>
> >
>
>
>
> --
> Harsh J
> Customer Ops. Engineer
> Cloudera | http://tiny.cloudera.com/about
>

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