diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt index 9be5da86e18..2e5e8d19c0a 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt +++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt @@ -459,6 +459,9 @@ Release 2.7.0 - UNRELEASED HDFS-7054. Make DFSOutputStream tracing more fine-grained (cmccabe) + HDFS.7849. Update documentation for enabling a new feature in rolling + upgrade ( J.Andreina via vinayakumarb ) + OPTIMIZATIONS HDFS-7454. Reduce memory footprint for AclEntries in NameNode. diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsRollingUpgrade.xml b/hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsRollingUpgrade.xml index e7d86986543..a62198f17bd 100644 --- a/hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsRollingUpgrade.xml +++ b/hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsRollingUpgrade.xml @@ -47,6 +47,15 @@ These two capabilities make it feasible to upgrade HDFS without incurring HDFS downtime. In order to upgrade a HDFS cluster without downtime, the cluster must be setup with HA.

+

+ If there is any new feature which is enabled in new software release, may not work with old software release after upgrade. + In such cases upgrade should be done by following steps. +

+
    +
  1. Disable new feature.
  2. +
  3. Upgrade the cluster.
  4. +
  5. Enable the new feature.
  6. +

Note that rolling upgrade is supported only from Hadoop-2.4.0 onwards.