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The following commit(s) were added to refs/heads/2.4 by this push:
new 2f03c80 MINOR: Update ZooKeeper upgrade notes
2f03c80 is described below
commit 2f03c805690ec9394036ba8123a71409731756be
Author: Manikumar Reddy <[email protected]>
AuthorDate: Fri Dec 20 00:47:12 2019 +0530
MINOR: Update ZooKeeper upgrade notes
Author: Manikumar Reddy <[email protected]>
Reviewers: Ismael Juma <[email protected]>, Magnus Edenhill
<[email protected]>, Colin Patrick McCabe <[email protected]>
Closes #7818 from omkreddy/zk-note
---
config/zookeeper.properties | 5 -----
docs/upgrade.html | 20 ++++++++++++++++----
2 files changed, 16 insertions(+), 9 deletions(-)
diff --git a/config/zookeeper.properties b/config/zookeeper.properties
index 8c186a3..90f4332 100644
--- a/config/zookeeper.properties
+++ b/config/zookeeper.properties
@@ -22,8 +22,3 @@ maxClientCnxns=0
# Set the port to something non-conflicting if choosing to enable this
admin.enableServer=false
# admin.serverPort=8080
-
-# Enable snapshot.trust.empty config if the ZK upgrade from 3.4.X to 3.5.6 is
failing
-# with "java.io.IOException: No snapshot found, but there are log entries"
error.
-# Check upgrade docs for more details.
-# snapshot.trust.empty=true
diff --git a/docs/upgrade.html b/docs/upgrade.html
index ce894d1..4394784 100644
--- a/docs/upgrade.html
+++ b/docs/upgrade.html
@@ -64,9 +64,21 @@
<p><b>Additional Upgrade Notes:</b></p>
<ol>
- <li>ZooKeeper has been upgraded to 3.5.6. Set
<code>snapshot.trust.empty=true</code> in <code>zookeeper.properties</code>
before the upgrade
- to avoid <a
href="https://issues.apache.org/jira/browse/ZOOKEEPER-3056";>ZOOKEEPER-3056</a>.
After the new version starts successfully, it is safe to remove this config.
- See <a
href="https://zookeeper.apache.org/doc/r3.5.6/zookeeperAdmin.html#sc_advancedConfiguration";>ZooKeeper
advanced configuration</a> for more details.
+ <li>ZooKeeper has been upgraded to 3.5.6. ZooKeeper upgrade from 3.4.X to
3.5.6 can fail if there are no snapshot files in 3.4 data directory.
+ This usually happens in test upgrades where ZooKeeper 3.5.6 is trying
to load an existing 3.4 data dir in which no snapshot file has been created.
+ For more details about the issue please refer to <a
href="https://issues.apache.org/jira/browse/ZOOKEEPER-3056";>ZOOKEEPER-3056</a>.
+ A fix is given in <a
href="https://issues.apache.org/jira/browse/ZOOKEEPER-3056";>ZOOKEEPER-3056</a>,
which is to set <code>snapshot.trust.empty=true</code>
+ config in <code>zookeeper.properties</code> before the upgrade. But we
have observed data loss in standalone cluster upgrades when using
+ <code>snapshot.trust.empty=true</code> config. For more details about
the issue please refer to <a
href="https://issues.apache.org/jira/browse/ZOOKEEPER-3644";>ZOOKEEPER-3644</a>.
+ So we recommend the safe workaround of copying empty <a
href="https://issues.apache.org/jira/secure/attachment/12928686/snapshot.0";>snapshot</a>
file to the 3.4 data directory,
+ if there are no snapshot files in 3.4 data directory. For more details
about the workaround please refer to <a
href="https://cwiki.apache.org/confluence/display/ZOOKEEPER/Upgrade+FAQ";>ZooKeeper
Upgrade FAQ</a>.
+ </li>
+ <li>
+ An embedded Jetty based <a
href="http://zookeeper.apache.org/doc/r3.5.6/zookeeperAdmin.html#sc_adminserver";>AdminServer</a>
added in ZooKeeper 3.5.
+ AdminServer is enabled by default in ZooKeeper and is started on port
8080.
+ AdminServer is disabled by default in the ZooKeeper config
(<code>zookeeper.properties</code>) provided by the Apache Kafka distribution.
+ Make sure to update your local <code>zookeeper.properties</code> file
with <code>admin.enableServer=false</code> if you wish to disable the
AdminServer.
+ Please refer <a
href="http://zookeeper.apache.org/doc/r3.5.6/zookeeperAdmin.html#sc_adminserver";>AdminServer
config</a> to configure the AdminServer.
</li>
</ol>
@@ -74,7 +86,7 @@
<ul>
<li>A new Admin API has been added for partition reassignments. Due to
changing the way Kafka propagates reassignment information,
it is possible to lose reassignment state in failure edge cases while
upgrading to the new version. It is not recommended to start reassignments
while upgrading.</li>
- <li>ZooKeeper has been upgraded from 3.4.14 to 3.5.5. TLS and dynamic
reconfiguration are supported by the new version.</li>
+ <li>ZooKeeper has been upgraded from 3.4.14 to 3.5.6. TLS and dynamic
reconfiguration are supported by the new version.</li>
<li>The <code>bin/kafka-preferred-replica-election.sh</code> command line
tool has been deprecated. It has been replaced by
<code>bin/kafka-leader-election.sh</code>.</li>
<li>The methods <code>electPreferredLeaders</code> in the Java
<code>AdminClient</code> class have been deprecated in favor of the methods
<code>electLeaders</code>.</li>
<li>Scala code leveraging the <code>NewTopic(String, int, short)</code>
constructor with literal values will need to explicitly call
<code>toShort</code> on the second literal.</li>
