anchor.diff:  [[rn_1.6.0_upgrade_notes]]
   == Upgrade Notes
   
  -* TBD
  +* Upgrading directly from Kudu 1.5.0 is supported and no special upgrade steps
  +  are required. A rolling upgrade may work, however it has not been tested.
  +  When upgrading Kudu, it is recommended to first shut down all Kudu processes
  +  across the cluster, then upgrade the software on all servers, then restart
  +  the Kudu processes on all servers in the cluster.
  +
  +[[rn_1.6.0_obsoletions]]
  +== Obsoletions
  +
  +* Support for Spark 1 (kudu-spark_2.10) has been **removed** in Kudu 1.6.0 and
  +  now only Spark 2 is supported. Spark 1 support was deprecated in Kudu 1.5.0.
   
   [[rn_1.6.0_deprecations]]
   == Deprecations
   
   * Support for Java 7 has been deprecated since Kudu 1.5.0 and may be removed in
     the next major release.
  -
  -* Support for Spark 1 (kudu-spark_2.10) has been deprecated since Kudu 1.6.0
  -  (TBD: no longer supported?)
   
   [[rn_1.6.0_new_features]]
   == New features
  
positive.code: 
  * Tablet servers now consider the health of all replicas of a tablet before
    deciding to evict one. This can improve stability of the Kudu cluster after
    experiencing multiple simultaneous daemon failures.
    (link:https://issues.apache.org/jira/browse/KUDU-2048[KUDU-2048])
  
  * Several performance improvements have been made to the Kudu master,
    particularly in concurrency of clients opening tables. This should improve
    performance in highly concurrent workloads.
  
  * The on-disk size metric for a tablet now includes all data and metadata.
    Previously, it excluded WAL segments and consensus metadata.
    (link:https://issues.apache.org/jira/browse/KUDU-1755[KUDU-1755])
  
  * Added verbose mode for the 'kudu cluster ksck' command to enable output
    of detailed information on the cluster's metadata, even when no errors are
  
negative.code:   settings: `--webserver_tls_ciphers` and `--webserver_tls_min_protocol`.
    These flags allow the advertised TLS ciphers and TLS protocol versions to be
    configured. Additionally, the webserver now excludes insecure legacy ciphers
    by default
    (see link:https://issues.apache.org/jira/browse/KUDU-2190[KUDU-2190]).
  
  == Optimizations and improvements
  
  * Kudu servers can now tolerate short interruptions in NTP clock
    synchronization. NTP synchronization is still required when any Kudu daemon
    starts up. If NTP synchronization is not available, diagnostic information
    is now logged to help pinpoint the issue
    (see link:https://issues.apache.org/jira/browse/KUDU-1578[KUDU-1578]).
  
  * Tablet server startup time has been improved significantly on servers
    containing large numbers of blocks.
  