Hi hdfs-dev, We propose merging the HDFS-5535 branch to trunk.
HDFS Rolling Upgrade is a feature to allow upgrading individual HDFS daemons. In Hadoop v2, HDFS supports highly-available (HA) namenode services and wire compatibility. These two capabilities make it feasible to upgrade HDFS without incurring HDFS downtime. We make such improvement in the HDFS-5535 branch. The HDFS-5535 branch is ready to be merged to trunk. As this being written, there are 48 subtasks in HDFS-5535; 44 subtasks are already completed. The core developments including feature development, unit tests and user doc, are already done. The merge patch posted a few ago already passed Jenkins. I will post a updated patch to trigger Jenkins again for the latest code base. The remaining JIRAs are: HDFS-3225: Revist upgrade snapshots, roll back, finalize to enable rolling upgrades (assigned to Sanjay) HDFS-6000: Avoid saving namespace when starting rolling upgrade (assigned to Jing) HDFS-6013: add rollingUpgrade information to latest UI (assigned to Vinay) HDFS-6016: Update datanode replacement policy to make writes more robust (assigned to Kihwal) HDFS-6000 will be committed soon. All other issues are further improvements which can be done after merge. The other remaining works are: - Revise the design doc - Post a test plan (Haohui is working on it.) - Execute the manual tests (Haohui and Fengdong will work on it.) The work was a collective effort of Nathan Roberts, Sanjay Radia, Suresh Srinivas, Kihwal Lee, Jing Zhao, Arpit Agarwal, Brandon Li, Haohui Mai, Vinayakumar B, Fengdong Yu, Chris Nauroth and Tsz-Wo Nicholas Sze, who have proposed the design, worked on the code, reviewed patches, tested the features and authored documentation. We thank everyone that who has gave us valuable comments and feedback on the feature. The vote runs for 7 days. Here is my +1 on the merge. Thanks. Tsz-Wo
