[ https://issues.apache.org/jira/browse/HDFS-2006?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13040092#comment-13040092 ]
Aaron T. Myers commented on HDFS-2006: -------------------------------------- One option to not waste memory resources for files/directories which do not have extended attributes set on them would be to go the same route as the {{INodeDirectory}} vs. {{INodeDirectoryWithQuota}} classes, i.e. have {{INodeFile}} and {{InodeFileWithXAttrs}}. Of course, this strategy requires that we implement classes for the matrix of all the different possible combinations of extra metadata types. A reasonable question to ask is whether we should concern ourselves all that much with the memory consumption of this, since the extended attributes will presumably be per-file. Since the NN's memory is dedicated to relatively few files and relatively many blocks, it may not matter much if we go with a fairly naive approach. Dhruba, do you have any data as to what percentage of the NN heap in a typical cluster goes to per-file metadata versus per-block metadata? > ability to support storing extended attributes per file > ------------------------------------------------------- > > Key: HDFS-2006 > URL: https://issues.apache.org/jira/browse/HDFS-2006 > Project: Hadoop HDFS > Issue Type: Improvement > Components: name-node > Reporter: dhruba borthakur > Assignee: dhruba borthakur > > It would be nice if HDFS provides a feature to store extended attributes for > files, similar to the one described here: > http://en.wikipedia.org/wiki/Extended_file_attributes. > The challenge is that it has to be done in such a way that a site not using > this feature does not waste precious memory resources in the namenode. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira