Problem: During a rolling upgrade to any of the releases listed below, the NameNode may report missing blocks after rolling multiple DataNodes. This is caused by a race condition with block reporting between the DataNode and the NameNode. No permanent data loss occurs, but data can be unavailable for up to six hours before the problem corrects itself.

Releases affected: CDH 5.0.6, 5.1.5, 5.2.5, 5.3.3, 5.4.1, 5.4.2

What to do:

To avoid the problem: Cloudera advises skipping the affected releases and installing a release containing the fix.

The releases containing the fix are: CDH 5.2.6, 5.3.4, 5.4.3

If you have already completed an upgrade to an affected release, or are installing a new cluster: In this case you can continue to run the release, or upgrade to a release that is not affected, as you choose.

Cloudera fully supports upgrade from Cloudera Enterprise 4 and CDH 4 to Cloudera Enterprise 5. Upgrade requires uninstalling the CDH 4 packages before installing CDH 5 packages. See the CDH 5 upgrade documentation for instructions.

You must upgrade to CDH 4, then to CDH 5. See the CDH 4 documentation for instructions on upgrading from CDH 3 to CDH 4.

Upgrading from CDH 4 requires an HDFS Upgrade. See Upgrading to CDH 5 from CDH 4 for further information.

Upgrading from CDH 4 to CDH 5.0.x installs Impala 1.3.2; this is a downgrade if you were running Impala 1.4.0 with CDH 4. To avoid a downgrade from Impala 1.4.0, upgrade CDH 4 to CDH 5.1.x rather than CDH 5.0.x; CDH 5.1.x installs Impala 1.4.1.

When installing Hadoop from Cloudera tarballs, you must build your own native libraries. The tarballs do not include libraries that are built for the different distributions and architectures.