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From Elazar Leibovich <elaz...@gmail.com>
Subject Re: Why Hadoop force using DNS?
Date Mon, 29 Jul 2013 14:50:21 GMT
Ease of use is a reason to support names, not to intentionally disallow raw
IPs. Not using names is convenient if you want to erect a temporary cluster
on a group of machines you don't own.

You have a user access, but name resolution is not always defined. As a
user you cannot change /etc/hosts.
On Jul 29, 2013 5:46 PM, "Chris Embree" <cembree@gmail.com> wrote:

> Just for clarity,  DNS as a service is NOT Required.  Name resolution is.
>  I use /etc/hosts files to identify all nodes in my clusters.
> One of the reasons for using Names over IP's is ease of use.  I would much
> rather use a hostname in my XML to identify NN, JT, etc. vs. some random
> string of numbers.
> On Mon, Jul 29, 2013 at 10:40 AM, Greg Bledsoe <greg@personal.com> wrote:
>> I can third this concern.  What purpose does this complexity increasing
>> requirement serve?  Why not remove it?
>> Greg Bledsoe
>> From: 武泽胜 <wuzesheng@xiaomi.com>
>> Reply-To: "user@hadoop.apache.org" <user@hadoop.apache.org>
>> Date: Mon, 29 Jul 2013 08:21:51 -0500
>> To: "user@hadoop.apache.org" <user@hadoop.apache.org>
>> Subject: Re: Why Hadoop force using DNS?
>> I have the same confusion, anyone who can reply to this will be very
>> appreciated.
>> From: Elazar Leibovich <elazarl@gmail.com>
>> Reply-To: "user@hadoop.apache.org" <user@hadoop.apache.org>
>> Date: Thursday, July 25, 2013 3:51 AM
>> To: user <user@hadoop.apache.org>
>> Subject: Why Hadoop force using DNS?
>> Looking at Hadoop source you can see that Hadoop relies on the fact each
>> node has resolvable name.
>> For example, Hadoop 2 namenode reverse look the up of each node that
>> connects to it. Also, there's no way way to tell a database to advertise an
>> UP as it's address. Setting datanode.network.interface to, say, eth1, would
>> cause Hadoop to reverse lookup UPs on eth1 and advertise the result.
>> Why is that? Using plain IPs is simple to set up, and I can't see a
>> reason not to support them?

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