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HDFS >> mail # user >> Re: Why Hadoop force using DNS?


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武泽胜 2013-07-29, 13:21
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Daryn Sharp 2013-07-29, 13:48
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Elazar Leibovich 2013-07-29, 15:11
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Greg Bledsoe 2013-07-29, 14:40
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Chris Embree 2013-07-29, 14:45
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Re: Why Hadoop force using DNS?
But even if you have permission to change /etc/hosts, /etc/hosts resolution seems to introduce instability for the reverse lookup leading to unpredictable results.  Dns gets used and if this doesn't match your /etc/hosts file, you have problems.  Or am I missing something?

Greg

From: Chris Embree <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Reply-To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>, "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Date: Mon, 29 Jul 2013 09:45:22 -0500
To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Subject: Re: Why Hadoop force using DNS?

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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
I can third this concern.  What purpose does this complexity increasing requirement serve?  Why not remove it?

Greg Bledsoe

From: 武泽胜 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Reply-To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Date: Mon, 29 Jul 2013 08:21:51 -0500
To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Reply-To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Date: Thursday, July 25, 2013 3:51 AM
To: user <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
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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Elazar Leibovich 2013-07-29, 14:50
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB