Hi, Please find the answers inline, if its helpful.
Thanks and Regargds, Vinayakumar B From: unmesha sreeveni [mailto:[email protected]] Sent: 09 December 2013 12:52 To: User Hadoop Subject: Which is hdfs? Can anyone tell me what is the difference between the below details My cluster is a remote system "sree". If you have set the fs.defaultFS as "hdfs://<namenode address>", then -copyFromLocal will copy to hdfs. 1. I have a "chck" file in my /home/sree I did > hadoop fs -copFromLocal /home/sree/chck > hadoop fs -ls -rw-r--r-- 1 sree supergroup 32 2013-12-03 14:27 chck I think you have done above operation from sree user. This is why -ls showing sree as the owner of the file. Since here you didn't pass the destination, by default file will be copied under /user/sree directory. -ls also shows from same directory. To make sure, you do '-ls /user/sree' whether chck file is now resided in hdfs? 2.After executing wordcount in my remote system my output folder looks like this drwxr-xr-x - hdfs supergroup 0 2013-11-19 09:41 wcout WordCount job is executing from the user hdfs, so -ls for the wcount is showing hdfs as owner. I have a confusion - which is hdfs? In my opinion, both files are in hdfs but under different user homes. The area where chck resided or wcout ? 3. Am i able to update/append "chck" file through MR job? HDFS supports only append from one client at a time. 4. -rw-r--r-- 1 hdfs supergroup 32 2013-12-03 14:27 myfile Am i able to update/append "myfile" file through MR job? Basically here you can update the file by creating the same file again. Updation to same file is not possible. **I read that updation is not allowed in hdfs** -- Thanks & Regards Unmesha Sreeveni U.B Junior Developer
