Mohit Anchlia 2013-01-16, 15:43
Mohammad Tariq 2013-01-16, 15:49
-Re: Loading file to HDFS with custom chunk structure
Mohammad Tariq 2013-01-16, 15:56
You might also find this link <https://github.com/cloudera/seismichadoop>useful.
On Wed, Jan 16, 2013 at 9:19 PM, Mohammad Tariq <[EMAIL PROTECTED]> wrote:
> Since SEGY files are flat binary files, you might have a tough
> time in dealing with them as their is no native InputFormat for
> that. You can strip off the EBCDIC+Binary header(Initial 3600
> Bytes) and store the SEGY file as Sequence Files, where each
> trace (Trace Header+Trace Data) would be the value and the
> trace no. could be the key.
> Otherwise you have to write a custom InputFormat to deal with
> that. It would enhance the performance as well, since Sequence
> Files are already in key-value form.
> Warm Regards,
> On Wed, Jan 16, 2013 at 9:13 PM, Mohit Anchlia <[EMAIL PROTECTED]>wrote:
>> Look at the block size concept in Hadoop and see if that is what you are
>> looking for
>> Sent from my iPhone
>> On Jan 16, 2013, at 7:31 AM, Kaliyug Antagonist <
>> [EMAIL PROTECTED]> wrote:
>> I want to load a SegY <http://en.wikipedia.org/wiki/SEG_Y> file onto
>> HDFS of a 3-node Apache Hadoop cluster.
>> To summarize, the SegY file consists of :
>> 1. 3200 bytes *textual header*
>> 2. 400 bytes *binary header*
>> 3. Variable bytes *data*
>> The 99.99% size of the file is due to the variable bytes data which is
>> collection of thousands of contiguous traces. For any SegY file to make
>> sense, it must have the textual header+binary header+at least one trace of
>> data. What I want to achieve is to split a large SegY file onto the Hadoop
>> cluster so that a smaller SegY file is available on each node for local
>> The scenario is as follows:
>> 1. The SegY file is large in size(above 10GB) and is resting on the
>> local file system of the NameNode machine
>> 2. The file is to be split on the nodes in such a way each node has a
>> small SegY file with a strict structure - 3200 bytes *textual header*+ 400 bytes
>> *binary header* + variable bytes *data*As obvious, I can't blindly
>> use FSDataOutputStream or hadoop fs -copyFromLocal as this may not ensure
>> the format in which the chunks of the larger file are required
>> Please guide me as to how I must proceed.
>> Thanks and regards !
Mohammad Tariq 2013-01-16, 15:38