Changing DN hostnames->IPs

[Otis Gospodnetic <ot...@yahoo.com>]

Hi,

Will NN get confused if I change the names of slaves from hostnames to IPs?
That is, if I've been running Hadoop for a while, and then decide to shut down all its daemons, switch to IPs, and start everything back up, will the master/NN still see all the DN slaves as before and will it know they are the same old set of DN slaves?

Thanks,
Otis
--
Sematext -- http://sematext.com/ -- Lucene - Solr - Nutch

Re: Changing DN hostnames->IPs

[Raghu Angadi <ra...@yahoo-inc.com>]

Short answer : renaming is not problem.

If you are running fairly recent Hadoop, NN does not store information 
about the DataNode persistently. So you should be ok in the sense 
NameNode does not depend on datanodes before the restart.

If you are running fairly old Hadoop, functionally it will ok. Only 
annoying thing would be that you might see all the previous datanodes 
listed as dead.

The recent trunk has some issues related using Datanode ID for some 
unclosed files.. but you may not be affected by that.

Raghu.

Otis Gospodnetic wrote:
> Hi,
> 
> Will NN get confused if I change the names of slaves from hostnames to IPs?
> That is, if I've been running Hadoop for a while, and then decide to shut down all its daemons, switch to IPs, and start everything back up, will the master/NN still see all the DN slaves as before and will it know they are the same old set of DN slaves?
> 
> Thanks,
> Otis
> --
> Sematext -- http://sematext.com/ -- Lucene - Solr - Nutch
>