hadoop-mapreduce-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Stanley Shi <s...@pivotal.io>
Subject Re: Local file system to access hdfs blocks
Date Thu, 28 Aug 2014 06:09:42 GMT
As far as I know, there's no combination of hadoop API can do that.
You can easily get the location of the block (on which DN), but there's no
way to get the local address of that block file.



On Thu, Aug 28, 2014 at 11:54 AM, Demai Ni <nidmgg@gmail.com> wrote:

> Yehia,
>
> No problem at all. I really appreciate your willingness to help. Yeah. now
> I am able to get such information through two steps, and the first step
> will be either hadoop fsck or getFileBlockLocations(). and then search
> the local filesystem, my cluster is using the default from CDH, which is
> /dfs/dn
>
> I would like to it programmatically, so wondering whether someone already
> done it? or maybe better a hadoop API call already implemented for this
> exact purpose
>
> Demai
>
>
> On Wed, Aug 27, 2014 at 7:58 PM, Yehia Elshater <y.z.elshater@gmail.com>
> wrote:
>
>> Hi Demai,
>>
>> Sorry, I missed that you are already tried this out. I think you can
>> construct the block location on the local file system if you have the block
>> pool id and the block id. If you are using cloudera distribution, the
>> default location is under /dfs/dn ( the value of dfs.data.dir,
>> dfs.datanode.data.dir configuration keys).
>>
>> Thanks
>> Yehia
>>
>>
>> On 27 August 2014 21:20, Yehia Elshater <y.z.elshater@gmail.com> wrote:
>>
>>> Hi Demai,
>>>
>>> You can use fsck utility like the following:
>>>
>>> hadoop fsck /path/to/your/hdfs/file -files -blocks -locations -racks
>>>
>>> This will display all the information you need about the blocks of your
>>> file.
>>>
>>> Hope it helps.
>>> Yehia
>>>
>>>
>>> On 27 August 2014 20:18, Demai Ni <nidmgg@gmail.com> wrote:
>>>
>>>> Hi, Stanley,
>>>>
>>>> Many thanks. Your method works. For now, I can have two steps approach:
>>>> 1) getFileBlockLocations to grab hdfs BlockLocation[]
>>>> 2) use local file system call(like find command) to match the block to
>>>> files on local file system .
>>>>
>>>> Maybe there is an existing Hadoop API to return such info in already?
>>>>
>>>> Demai on the run
>>>>
>>>> On Aug 26, 2014, at 9:14 PM, Stanley Shi <sshi@pivotal.io> wrote:
>>>>
>>>> I am not sure this is what you want but you can try this shell command:
>>>>
>>>> find [DATANODE_DIR] -name [blockname]
>>>>
>>>>
>>>> On Tue, Aug 26, 2014 at 6:42 AM, Demai Ni <nidmgg@gmail.com> wrote:
>>>>
>>>>> Hi, folks,
>>>>>
>>>>> New in this area. Hopefully to get a couple pointers.
>>>>>
>>>>> I am using Centos and have Hadoop set up using cdh5.1(Hadoop 2.3)
>>>>>
>>>>> I am wondering whether there is a interface to get each hdfs block
>>>>> information in the term of local file system.
>>>>>
>>>>> For example, I can use "Hadoop fsck /tmp/test.txt -files -blocks
>>>>> -racks" to get blockID and its replica on the nodes, such as: repl =3[
>>>>> /rack/hdfs01, /rack/hdfs02...]
>>>>>
>>>>>  With such info, is there a way to
>>>>> 1) login to hfds01, and read the block directly at local file system
>>>>> level?
>>>>>
>>>>>
>>>>> Thanks
>>>>>
>>>>> Demai on the run
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Regards,
>>>> *Stanley Shi,*
>>>>
>>>>
>>>
>>
>


-- 
Regards,
*Stanley Shi,*

Mime
View raw message