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From Bertrand Dechoux <decho...@gmail.com>
Subject Re: Question about DataNode
Date Thu, 27 Feb 2014 10:08:49 GMT
I am not sure what your question is. You might want to be more explicit and
read more about Hadoop architecture and the roles of the various daemons. A
directory is only metadata so you can mess around with DataNodes if you
want but they are not involved.



Bertrand Dechoux

On Thu, Feb 27, 2014 at 10:12 AM, Juan Carlos <jucaf1@gmail.com> wrote:

> Hi Edward,
> maybe you are sending your request to the master from the slave. I don't
> are sure, but I think that secondary never answer any request, neither read
> request, and you have to modify your config files by hand to change your
> slave to be master.
> I haven't tested so much with master/slave configurations, I only tested
> with QJM and NFS syncronizations, in these cases whenever you start
> namenodes they first get syncronized before being able to promote to active
> namenode by checking journalnodes or NFS looking for changes in metadata to
> update them.
> 2014-02-27 9:52 GMT+01:00 EdwardKing <zhangsc@neusoft.com>:
>  Two node,one is master,another is slave, I kill DataNode under slave,
>> then create directory by dfs command under master machine:
>> [hadoop@master]$./start-all.sh
>>  [hadoop@slave]$ jps
>> 9917 DataNode
>> 10152 Jps
>> [hadoop@slave]$ kill -9 9917
>> [hadoop@master]$ hadoop dfs -mkdir test
>> [hadoop@master]$ hadoop dfs -ls
>> drwxr-xr-x   - hadoop supergroup          0 2014-02-27 00:15 test
>> I guess test directory can't exist under slave,because slave is killed.
>> Right?
>> Then I restart service under master,like follows:
>>  [hadoop@master]$./start-all.sh
>> This time I find slave also contains test directory, why? Is hadoop2.2.0
>> can automatic recovery?
>> Any idea will be appreciated.
>> Best regards,
>> Edward
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