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From Jitendra Yadav <jeetuyadav200...@gmail.com>
Subject Re: hadoop cares about /etc/hosts ?
Date Wed, 11 Sep 2013 08:03:53 GMT
Hi,

So what you were expecting while pinging master?

As per my understanding it is working fine.Well there is no sense of using
localhost and hostname on same ip, for localhost it's always preferred to
use loopback method i.e 127.0.0.1

Hope this will help you.

Regards
Jitendra
On Wed, Sep 11, 2013 at 7:05 AM, Cipher Chen <cipher.chen2012@gmail.com>wrote:

>  So
> for the first *wrong* /etc/hosts file, the sequence would be :
> find hdfs://master:54310
> find master -> 192.168.6.10 (*but it already got ip here*)
> find 192.168.6.10 -> localhost
> find localhost -> 127.0.0.1
>
>
> The other thing, when 'ping master', i would got reply from '192.168.6.10'
> instead of 127.0.0.1.
> So it's not simply the Name Resolution on the os level. Or i'm totally
> wrong?
>
>
>
> On Tue, Sep 10, 2013 at 11:13 PM, Vinayakumar B <
> vinay.opensource@gmail.com> wrote:
>
>> Ensure that for each ip there is only one hostname configured in
>> /etc/hosts file.
>>
>> If you configure multiple different hostnames for same ip then os will
>> chose first one when finding hostname using ip. Similarly for ip using
>> hostname.
>>
>> Regards,
>> Vinayakumar B
>>  On Sep 10, 2013 9:27 AM, "Chris Embree" <cembree@gmail.com> wrote:
>>
>>> This sound entirely like an OS Level problem and is slightly outside of
>>> the scope of this list, however.  I'd suggest you look at your
>>> /etc/nsswitch.conf file and ensure that the hosts: line says
>>> hosts: files dns
>>>
>>> This will ensure that names are resolved first by /etc/hosts, then by
>>> DNS.
>>>
>>> Please also ensure that all of your systems have the same configuration
>>> and that your NN, JT, SNN, etc. are all using the correct/same hostname.
>>>
>>> This is basic Name Resolution, please do not confuse this with a Hadoop
>>> issue. IMHO
>>>
>>>
>>> On Mon, Sep 9, 2013 at 10:05 PM, Cipher Chen <cipher.chen2012@gmail.com>wrote:
>>>
>>>>  Sorry i didn't express it well.
>>>>
>>>> conf/masters:
>>>> master
>>>>
>>>> conf/slaves:
>>>> master
>>>> slave
>>>>
>>>> The /etc/hosts file which caused the problem (start-dfs.sh failed):
>>>>  127.0.0.1       localhost
>>>>  192.168.6.10    localhost
>>>> ###
>>>>
>>>> 192.168.6.10    tulip master
>>>> 192.168.6.5     violet slave
>>>>
>>>> But when I commented the line appended with hash,
>>>> 127.0.0.1       localhost
>>>> #
>>>> 192.168.6.10    localhost
>>>> ###
>>>>
>>>> 192.168.6.10    tulip master
>>>> 192.168.6.5     violet slave
>>>>
>>>> The namenode starts successfully.
>>>> I can't figure out *why*.
>>>> How does hadoop decide which host/hostname/ip to be the namenode?
>>>>
>>>> BTW: How could namenode care about conf/masters and conf/slaves,
>>>> since it's the host who run start-dfs.sh would be the namenode.
>>>> Namenode doesn't need to check those confs.
>>>> Nodes listed in conf/masteres would be SecondaryNameNode, isn't it?
>>>> I
>>>>
>>>>
>>>> On Mon, Sep 9, 2013 at 10:39 PM, Jitendra Yadav <
>>>> jeetuyadav200890@gmail.com> wrote:
>>>>
>>>>> Means your $HADOOP_HOME/conf/masters file content.
>>>>>
>>>>>
>>>>> On Mon, Sep 9, 2013 at 7:52 PM, Jay Vyas <jayunit100@gmail.com>
wrote:
>>>>>
>>>>>> Jitendra:  When you say " check your masters file content"  what
are
>>>>>> you referring to?
>>>>>>
>>>>>>
>>>>>> On Mon, Sep 9, 2013 at 8:31 AM, Jitendra Yadav <
>>>>>> jeetuyadav200890@gmail.com> wrote:
>>>>>>
>>>>>>> Also can you please check your masters file content in hadoop
conf
>>>>>>> directory?
>>>>>>>
>>>>>>> Regards
>>>>>>> JItendra
>>>>>>>
>>>>>>> On Mon, Sep 9, 2013 at 5:11 PM, Olivier Renault <
>>>>>>> orenault@hortonworks.com> wrote:
>>>>>>>
>>>>>>>> Could you confirm that you put the hash in front of 192.168.6.10
>>>>>>>> localhost
>>>>>>>>
>>>>>>>> It should look like
>>>>>>>>
>>>>>>>> # 192.168.6.10    localhost
>>>>>>>>
>>>>>>>> Thanks
>>>>>>>> Olivier
>>>>>>>>  On 9 Sep 2013 12:31, "Cipher Chen" <cipher.chen2012@gmail.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>>   Hi everyone,
>>>>>>>>>   I have solved a configuration problem due to myself
in hadoop
>>>>>>>>> cluster mode.
>>>>>>>>>
>>>>>>>>> I have configuration as below:
>>>>>>>>>
>>>>>>>>>   <property>
>>>>>>>>>     <name>fs.default.name</name>
>>>>>>>>>     <value>hdfs://master:54310</value>
>>>>>>>>>   </property>
>>>>>>>>>
>>>>>>>>> a
>>>>>>>>> nd the hosts file:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /etc/hosts:
>>>>>>>>> 127.0.0.1       localhost
>>>>>>>>>  192.168.6.10    localhost
>>>>>>>>> ###
>>>>>>>>>
>>>>>>>>> 192.168.6.10    tulip master
>>>>>>>>> 192.168.6.5     violet slave
>>>>>>>>>
>>>>>>>>> a
>>>>>>>>> nd when i was trying to start-dfs.sh, namenode failed
to start.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> namenode log hinted that:
>>>>>>>>> 13/09/09 17:09:02 INFO namenode.NameNode: Namenode up
at:
>>>>>>>>> localhost/192.168.6.10:54310
>>>>>>>>> ...
>>>>>>>>> 13/09/09 17:09:10 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 0 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:11 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 1 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:12 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 2 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:13 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 3 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:14 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 4 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:15 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 5 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:16 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 6 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:17 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 7 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:18 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 8 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> 13/09/09 17:09:19 INFO ipc.Client: Retrying connect to
server:
>>>>>>>>> localhost/127.0.0.1:54310. Already tried 9 time(s); retry
policy
>>>>>>>>> is RetryUpToMaximumCountWithF>
>>>>>>>>> ...
>>>>>>>>>
>>>>>>>>> Now I know deleting the line "192.168.6.10    localhost
 ###
>>>>>>>>> "
>>>>>>>>> would fix this.
>>>>>>>>> But I still don't know
>>>>>>>>>
>>>>>>>>> why hadoop would resolve "master" to "localhost/127.0.0.1."
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Seems http://blog.devving.com/why-does-hbase-care-about-etchosts/explains
this,
>>>>>>>>> I'm not quite sure.
>>>>>>>>> Is there any
>>>>>>>>>  other
>>>>>>>>> explanation to this?
>>>>>>>>>
>>>>>>>>> Thanks.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>  --
>>>>>>>>> Cipher Chen
>>>>>>>>>
>>>>>>>>
>>>>>>>> CONFIDENTIALITY NOTICE
>>>>>>>> NOTICE: This message is intended for the use of the individual
or
>>>>>>>> entity to which it is addressed and may contain information
that is
>>>>>>>> confidential, privileged and exempt from disclosure under
applicable law.
>>>>>>>> If the reader of this message is not the intended recipient,
you are hereby
>>>>>>>> notified that any printing, copying, dissemination, distribution,
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>>>>>>>> you have received this communication in error, please contact
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>>>>>>>> immediately and delete it from your system. Thank You.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Jay Vyas
>>>>>> http://jayunit100.blogspot.com
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Cipher Chen
>>>>
>>>
>>>
>
>
> --
> Cipher Chen
>

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