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new 1ecf8c0 Update ZooKeeper upgrade notes
1ecf8c0 is described below
commit 1ecf8c02e913e0e593a3618e718a4898f97bea70
Author: Manikumar Reddy <[email protected]>
AuthorDate: Fri Dec 20 00:56:52 2019 +0530
Update ZooKeeper upgrade notes
---
24/upgrade.html | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/24/upgrade.html b/24/upgrade.html
index edfba5d..4394784 100644
--- a/24/upgrade.html
+++ b/24/upgrade.html
@@ -67,13 +67,11 @@
<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>.
- For multi-node ZooKeeper cluster upgrades, 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.
- For standalone cluster upgrades, we have observed a data loss issue
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>.
- The workaround is need to manually copy the <a
href="https://issues.apache.org/jira/secure/attachment/12928686/snapshot.0";>snapshot</a>
file to the 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>.
+ 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.
