3 Known Issues and Workarounds

Learn about the known issues at the time of release.

This chapter includes the following sections:

3.1 SSL Restrictions Cause Cluster Failure


When upgrading to Java 8 Update 151 (8u151) or higher, a cluster may fail due to tighter security checks on algorithm constraints. The following error is emitted:

Error generating DH server key exchange; The security strength of SHA-1 digest algorithm is not sufficient for this key size


Regenerate SSL certificates and explicitly set the key algorithm and key size. For example:

keytool -genkeypair -keyalg RSA -keysize 2048 -dname "cn=administrator, ou=Coherence, o=Oracle, c=US" -alias admin -keypass password -keystore /test/server.jks -storepass password -validity 180

3.2 Changing the Partition Count When Using Active Persistence


The partition count cannot be changed when using active persistence. If you change a services partition count, then on restart of the services all active data is moved to the persistence trash and must be recovered after the original partition count is restored. Data that is persisted can only be recovered to services running with the same partition count.

Ensure that the partition count is not modified if active persistence is being used. If the partition count is changed, then a message similar to the following is displayed when the services are started:

<Warning> (thread=DistributedCache:DistributedCachePersistence, member=1):
Failed to recover partition 0 from SafeBerkeleyDBStore(...); partition-count
mismatch 501(persisted) != 277(service); reinstate persistent store from
trash once validation errors have been resolved

The message indicates that the change in the partition-count is not supported and the current active data has been copied to the trash directory.


To recover the data:

  1. Shutdown the entire cluster.

  2. Remove the current active directory contents for the cluster and service affected on each cluster member.

  3. Copy (recursively) the contents of the trash directory for each service to the active directory.

  4. Restore the partition count to the original value.

  5. Restart the cluster.

3.3 Impact of Generics

When using generics with Federated Caching and Persistence, you must:

  • Ensure that federated caches across a federation are configured to use the same types as no runtime-type-checking is performed between clusters in a federation.

  • Ensure that recoverable caches are consistently configured to use the same types during restarts as no runtime-type-checking is performed.

3.4 Support for JVisualVM Plugin

The Coherence JvisualVM Plugin is supported for Coherence 3.7.1.X and above. Using the plugin to connect to older clusters is not supported.