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HDFS, mail # user - Re: Name node and data node replacement


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Re: Name node and data node replacement
oc tsdb 2013-12-11, 11:50
Hi,

Does NN log anywhere saying that 'one of DN is down and not reachable,so
replicating damaged DN data to another DN'?

Thanks

On Wed, Dec 11, 2013 at 2:10 PM, Jitendra Yadav
<[EMAIL PROTECTED]>wrote:

> Yes you are right. It will periodically checks the under replicated blocks
> information and place those blocks on available data nodes if required.
>
> Regards
> Jitendra
>
>
> On Wed, Dec 11, 2013 at 1:57 PM, oc tsdb <[EMAIL PROTECTED]> wrote:
>
>> Hi,
>>
>> Thanks for your response.
>>
>> You mean NN will always try to maintain number of replicas as configured
>> even if one DN goes down and unable to come up?
>>
>> Thanks
>> -OC
>>
>>
>>
>> On Mon, Dec 9, 2013 at 8:18 PM, Daryn Sharp <[EMAIL PROTECTED]> wrote:
>>
>>> To recover a NN, you probably want to use the HA feature.  If not, try
>>> writing your edits to a nfs volume in additional to the local fs.
>>>
>>> There is no need to recover a DN.  The NN compensates for a lost DN by
>>> using the other remaining replicas to create a new replica on another DN.
>>>
>>> Daryn
>>>
>>> On Dec 9, 2013, at 5:52 AM, oc tsdb <[EMAIL PROTECTED]> wrote:
>>>
>>> > Hi,
>>> >
>>> > I am trying to understand,how to recover a Name node or Data node
>>> failure in case if those nodes are unable to come up due to unexpected
>>> issues.
>>> >
>>> > Is there a way to replace Name node with new name node without loosing
>>> data.I mean new Name node should have all the data from original Name node.
>>> > Similarly for Data node.
>>> >
>>> >
>>> > Thanks
>>> > -OC
>>> >
>>> >
>>>
>>>
>>
>