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From Bruno Mahé (Commented) (JIRA) <>
Subject [jira] [Commented] (BIGTOP-456) Consider splitting homedir between mapred and hdfs users?
Date Fri, 16 Mar 2012 00:20:41 GMT


Bruno Mahé commented on BIGTOP-456:

This is why /var/run/hadoop belongs to the group hadoop and is writable. So both daemons can
write to it.
By default it is set to:
{noformat}drwxrwxr-x   2 root      hadoop    4096 Mar 15 14:31 hadoop{noformat}

And I see the home dir of these users not being set to /var/run/hadoop but rather /usr/lib/hadoop:
[root@172 ~]# grep hadoop /etc/passwd
mapred:x:497:494:Hadoop MapReduce:/usr/lib/hadoop:/bin/bash
hdfs:x:496:495:Hadoop HDFS:/usr/lib/hadoop:/bin/bash

But I agree that separating the pid dir of these 2 users would make sense.

Regarding /run vs /var/run, given we also strive to support older GNU/Linux distributions
such as CentOS/RHEL 5 and others, I would rather stay on /var/run for consistency.
Unless there is a compelling reason to have a specific packaging path for cases where /run
is available. But that would make maintenance of the packages more complex, so it has to be
worth it.
> Consider splitting homedir between mapred and hdfs users?
> ---------------------------------------------------------
>                 Key: BIGTOP-456
>                 URL:
>             Project: Bigtop
>          Issue Type: Improvement
>          Components: General
>    Affects Versions: 0.1.0
>         Environment: RPMs
>            Reporter: Harsh J
>            Priority: Minor
> Both "mapred" and "hdfs" users have the same home dir.
> A user reported having some problems with their config management system overwriting
the "mapred" user permissions of the PID directory (Which is also its homedir) with those
of the "hdfs" user (Same homedir as "mapred" user), which causes the tasktracker process to
fail to start, since it now cannot write to the PID dir.
> Although the config system can be fixed not to do that, if both users had separate home
dirs, this would not have been a problem, and the separation would have only been logical.
> I think after the username separation Hadoop has had in packaging terms, the homedir
split does make sense.
> Its just 1/0.22 versions of Hadoop and their packages that could be affected by this.
> Presently, for 0.23+, I think we have /var/run/hadoop/ for all things HDFS (Should we
rename?) and /var/run/yarn/ for all things MapReduce2 which makes sense and should be good

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