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Re: Hadoop noob question
You'r welcome :)

Warm Regards,
Tariq
cloudfront.blogspot.com
On Sat, May 11, 2013 at 10:46 PM, Rahul Bhattacharjee <
[EMAIL PROTECTED]> wrote:

> Thanks Tariq!
>
>
> On Sat, May 11, 2013 at 10:34 PM, Mohammad Tariq <[EMAIL PROTECTED]>wrote:
>
>> @Rahul : Yes. distcp can do that.
>>
>> And, bigger the files lesser the metadata hence lesser memory consumption.
>>
>> Warm Regards,
>> Tariq
>> cloudfront.blogspot.com
>>
>>
>> On Sat, May 11, 2013 at 9:40 PM, Rahul Bhattacharjee <
>> [EMAIL PROTECTED]> wrote:
>>
>>> IMHO,I think the statement about NN with regard to block metadata is
>>> more like a general statement. Even if you put lots of small files of
>>> combined size 10 TB , you need to have a capable NN.
>>>
>>> can disct cp be used to copy local - to - hdfs ?
>>>
>>> Thanks,
>>> Rahul
>>>
>>>
>>> On Sat, May 11, 2013 at 9:35 PM, Nitin Pawar <[EMAIL PROTECTED]>wrote:
>>>
>>>> absolutely rite Mohammad
>>>>
>>>>
>>>> On Sat, May 11, 2013 at 9:33 PM, Mohammad Tariq <[EMAIL PROTECTED]>wrote:
>>>>
>>>>> Sorry for barging in guys. I think Nitin is talking about this :
>>>>>
>>>>> Every file and block in HDFS is treated as an object and for each
>>>>> object around 200B of metadata get created. So the NN should be powerful
>>>>> enough to handle that much metadata, since it is going to be in-memory.
>>>>> Actually memory is the most important metric when it comes to NN.
>>>>>
>>>>> Am I correct @Nitin?
>>>>>
>>>>> @Thoihen : As Nitin has said, when you talk about that much data you
>>>>> don't actually just do a "put". You could use something like "distcp" for
>>>>> parallel copying. A better approach would be to use a data aggregation tool
>>>>> like Flume or Chukwa, as Nitin has already pointed. Facebook uses their own
>>>>> data aggregation tool, called Scribe for this purpose.
>>>>>
>>>>> Warm Regards,
>>>>> Tariq
>>>>> cloudfront.blogspot.com
>>>>>
>>>>>
>>>>> On Sat, May 11, 2013 at 9:20 PM, Nitin Pawar <[EMAIL PROTECTED]>wrote:
>>>>>
>>>>>> NN would still be in picture because it will be writing a lot of meta
>>>>>> data for each individual file. so you will need a NN capable enough which
>>>>>> can store the metadata for your entire dataset. Data will never go to NN
>>>>>> but lot of metadata about data will be on NN so its always good idea to
>>>>>> have a strong NN.
>>>>>>
>>>>>>
>>>>>> On Sat, May 11, 2013 at 9:11 PM, Rahul Bhattacharjee <
>>>>>> [EMAIL PROTECTED]> wrote:
>>>>>>
>>>>>>> @Nitin , parallel dfs to write to hdfs is great , but could not
>>>>>>> understand the meaning of capable NN. As I know , the NN would not be a
>>>>>>> part of the actual data write pipeline , means that the data would not
>>>>>>> travel through the NN , the dfs would contact the NN from time to time to
>>>>>>> get locations of DN as where to store the data blocks.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Rahul
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Sat, May 11, 2013 at 4:54 PM, Nitin Pawar <
>>>>>>> [EMAIL PROTECTED]> wrote:
>>>>>>>
>>>>>>>> is it safe? .. there is no direct answer yes or no
>>>>>>>>
>>>>>>>> when you say , you have files worth 10TB files and you want to
>>>>>>>> upload  to HDFS, several factors come into picture
>>>>>>>>
>>>>>>>> 1) Is the machine in the same network as your hadoop cluster?
>>>>>>>> 2) If there guarantee that network will not go down?
>>>>>>>>
>>>>>>>> and Most importantly I assume that you have a capable hadoop
>>>>>>>> cluster. By that I mean you have a capable namenode.
>>>>>>>>
>>>>>>>> I would definitely not write files sequentially in HDFS. I would
>>>>>>>> prefer to write files in parallel to hdfs to utilize the DFS write features
>>>>>>>> to speed up the process.
>>>>>>>> you can hdfs put command in parallel manner and in my experience it
>>>>>>>> has not failed when we write a lot of data.
>>>>>>>>
>>>>>>>>
>>>>>>>> On Sat, May 11, 2013 at 4:38 PM, maisnam ns <[EMAIL PROTECTED]>wrote:
>>>>>>>>
>>>>>>>>> @Nitin Pawar , thanks for clearing my doubts .
>>>>>>>>>
>>>