Hi all, I discussed this with a couple folks over the weekend who are involved in the project, but wanted to let the dev community at large know:
I'm planning on creating a new SVN branch for HDFS-1073 and its subtasks. For those not aware, HDFS-1073 is a rethinking of how the NN, 2NN, and BackupNode store images and edit logs on disk. This will help make HA more manageable down the line and has a lot of operational benefits as described in the JIRA. The "related work" is the addition of transaction IDs to the persistent storage of the NN, and some refactoring in the edit log subsystem. The reasoning behind creating a branch is that, since this is a fairly large change, it is easier to develop through a number of subtasks. But at some of the intermediate points, various components will be temporarily broken. Developing on a branch will allow us to make incremental progress without worrying about keeping all tests green after every change. We will of course make sure all tests pass before merging back into trunk. There will also be another opportunity to review before the merge into trunk. This is the same development methodology as was done for the 0.21 Append work and is now being used for Federation. Given that there will be another opportunity to review these changes before merging into trunk, I would also like to propose that Ivan Kelly be granted the ability to "+1" patches on this branch despite not being an HDFS committer. Ivan is actively contributing on this project and understands the code well. Unless there are any objections, I will create this branch and an associated Fix Version on JIRA tonight. Thanks! -Todd -- Todd Lipcon Software Engineer, Cloudera
