[ https://issues.apache.org/jira/browse/HDFS-1094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12886867#action_12886867 ]
Rodrigo Schmidt commented on HDFS-1094: --------------------------------------- I'm not sure I understand what you mean by node group. Sometimes it seems to be the machines in which you can have replicas for the same block (always triples), and sometimes it seems to be the bigger set from which you can pick replicas from. Which one is the right one? I guess a more formal definition could break the redundancy. > Intelligent block placement policy to decrease probability of block loss > ------------------------------------------------------------------------ > > Key: HDFS-1094 > URL: https://issues.apache.org/jira/browse/HDFS-1094 > Project: Hadoop HDFS > Issue Type: Improvement > Components: name-node > Reporter: dhruba borthakur > Assignee: Rodrigo Schmidt > Attachments: prob.pdf, prob.pdf > > > The current HDFS implementation specifies that the first replica is local and > the other two replicas are on any two random nodes on a random remote rack. > This means that if any three datanodes die together, then there is a > non-trivial probability of losing at least one block in the cluster. This > JIRA is to discuss if there is a better algorithm that can lower probability > of losing a block. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.