[ http://issues.apache.org/jira/browse/HADOOP-227?page=comments#action_12453772 ] Milind Bhandarkar commented on HADOOP-227: ------------------------------------------
Well, the sort-merge approach does not seem performant anyway if the number of renames is large. So, I am adding the copy-on-write (Dhruba's comment on HADOOP-334) to the proposal. This proposal suggests adding a clone member to every node. While checkpointing is in progress, change to a node is instead made to a clone. When periodic checkpointing is finished, the checkpointer resets the clones by making them actual nodes. I will write up a better description and post as RFC soon. > Namespace check pointing is not performed until the namenode restarts. > ---------------------------------------------------------------------- > > Key: HADOOP-227 > URL: http://issues.apache.org/jira/browse/HADOOP-227 > Project: Hadoop > Issue Type: Bug > Components: dfs > Affects Versions: 0.2.0 > Reporter: Konstantin Shvachko > Assigned To: Konstantin Shvachko > > In current implementation when the name node starts, it reads its image file, > then > the edits file, and then saves the updated image back into the image file. > The image file is never updated after that. > In order to provide the system reliability reliability the namespace > information should > be check pointed periodically, and the edits file should be kept relatively > small. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
