Re: DNS.reverseDns() fallback

[Johannes Zillmann <jz...@googlemail.com>]

Thanks for your input!
I added an issue for improving the fallback mechanism: https://issues.apache.org/jira/browse/HADOOP-6797

Johannes

On May 28, 2010, at 7:46 PM, Michael Segel wrote:

> 
> 
> 
>> Date: Fri, 28 May 2010 13:13:56 -0400
>> Subject: Re: DNS.reverseDns() fallback
>> From: esammer@cloudera.com
>> To: common-user@hadoop.apache.org
>> CC: core-user@hadoop.apache.org
> [SNIP]
>>> IMHO, after looking at this issue, it really doesn't matter since the cloud shouldn't be getting a lot of external traffic except on the name node/job tracker nodes which could be multi-homed.
>> 
>> It might be useful in the case where you're streaming data off of HDFS
>> directly to clients rather than in the MR or HBase case. Data import /
>> export comes to mind. Remember that clients establish a direct
>> connection to data nodes so a multihomed NN is insufficient. In that
>> case, "external" doesn't necessarily mean a public (routable) IP, but
>> simply another network. We've seen use cases for this in some
>> installations. One example is a data aggregation or ingestion network
>> is separate from the Hadoop internal network and you'd like to get
>> data into HDFS.
>> 
> 
> Eric,
> I don't disagree that it is useful. 
> 
> I was just offering up an alternative cloud design which would work as a work-around.
> As you point out, clients need to talk to all of the nodes.
> So you can make your name node your gateway for the rest of the cloud.
> (not a great idea but it works.)
> Or you can launch your jobs from a client or clients, who are multi-homed.
> 
> If you're a Cloudera fan, you could use the cloudera desktop to launch jobs.
> So as long as that machine is visible to the cloud, you'll be OK too. ;-)
> 
> I don't really recommend this, but its still a viable solution.
> 
> -Mike
> 
> 
> 		 	   		  
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