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https://issues.apache.org/jira/browse/ZOOKEEPER-261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15727937#comment-15727937
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ASF GitHub Bot commented on ZOOKEEPER-261:
------------------------------------------
Github user hanm commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/120#discussion_r91235960
--- Diff:
src/java/main/org/apache/zookeeper/server/persistence/FileTxnSnapLog.java ---
@@ -132,6 +137,9 @@ public FileTxnSnapLog(File dataDir, File snapDir)
throws IOException {
txnLog = new FileTxnLog(this.dataDir);
snapLog = new FileSnap(this.snapDir);
+
+ autoCreateDB =
Boolean.parseBoolean(System.getProperty(ZOOKEEPER_DB_AUTOCREATE,
--- End diff --
>> Is that in accord with Zookeeper style?
I see - I thought the new property was not end user facing since there is
no associated documents added here. Since the property
"zookeeper.db.autocreate" is exposed to user some doc could be added to
ZooKeeperAdmin.html (similarly like how the existing
"zookeeper.datadir.autocreate" is documented there) to describe the motivation
/ usage of the property.
> Reinitialized servers should not participate in leader election
> ---------------------------------------------------------------
>
> Key: ZOOKEEPER-261
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-261
> Project: ZooKeeper
> Issue Type: Improvement
> Components: leaderElection, quorum
> Reporter: Benjamin Reed
>
> A server that has lost its data should not participate in leader election
> until it has resynced with a leader. Our leader election algorithm and
> NEW_LEADER commit assumes that the followers voting on a leader have not lost
> any of their data. We should have a flag in the data directory saying whether
> or not the data is preserved so that the the flag will be cleared if the data
> is ever cleared.
> Here is the problematic scenario: you have have ensemble of machines A, B,
> and C. C is down. the last transaction seen by C is z. a transaction, z+1, is
> committed on A and B. Now there is a power outage. B's data gets
> reinitialized. when power comes back up, B and C comes up, but A does not. C
> will be elected leader and transaction z+1 is lost. (note, this can happen
> even if all three machines are up and C just responds quickly. in that case C
> would tell A to truncate z+1 from its log.) in theory we haven't violated our
> 2f+1 guarantee, since A is failed and B still hasn't recovered from failure,
> but it would be nice if when we don't have quorum that system stops working
> rather than works incorrectly if we lose quorum.
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