Hi Jun Tan,
As Subroto pointed Hadoop doesn’t depend on the number of cores but we can tune the parameters based on the no of cores and type of job we are running for better performance. We can start multiple data nodes or task trackers irrespective of single core or multi core by doing some changes in the script and configuration files. You can have a look into this, for what all changes need to do for starting multiple data nodes in a single machine. http://www.mail-archive.com/hdfs-user@hadoop.apache.org/msg01353.html Devaraj K _____ From: 谭军 [mailto:tanjun_2...@163.com] Sent: Monday, August 08, 2011 2:49 PM To: mapreduce-user@hadoop.apache.org; subroto.san...@huawei.com Subject: Re:RE: Can I use the cores of each CPU to be the datanodes instead of CPU? Hi Subroto, I'm sorry for my poor English. Are you thinking about CPU core to Hadoop process mapping? Maybe this is the issue. 2 computers with 2 CPUs. Each CPU has 2 cores. Now I have 2 physical datanodes. Can I get 4 physical datanodes? I don't know wether I make my point clear? -- Regards! Jun Tan 在 2011-08-08 17:05:31，"Subroto Sanyal" <subrotosan...@huawei.com> 写道： Hi Jun, Sorry, I didn’t get your question properly….. :-( Are you thinking in terms of Virtual Machines running on same physical server? Are you thinking about CPU core to Hadoop process mapping? As per my understanding, Hadoop doesn’t have intelligence of different cores (ideally application should be independent of hardware details) It is possible to run multiple instance of DataNode in same physical server, provide the configurations are different for each DataNode process. Regards, Subroto Sanyal _____ From: 谭军 [mailto:tanjun_2...@163.com] Sent: Monday, August 08, 2011 2:16 PM To: mapreduce Subject: Can I use the cores of each CPU to be the datanodes instead of CPU? Hi, I have 2 computers each of which is double-core CPU. The 2 computers are datanodes and another computer is the namenode. Now, I want to increase the number of datanode but no more computers available. Can I use the 4 cores of the 2 computers to be 4 datanodes? -- Best regards! Jun Tan
