https://jira.opendaylight.org This file is an XML representation of an issue en-us 8.20.10 820010 22-06-2022 https://jira.opendaylight.org/browse/CONTROLLER-1067 controller <p>Let's say we have a Follower with 5 applied entries in it's in-memory journal and a snapshot is triggered on the Follower. With the current logic the in-memory journal will be emptied and all the 5 entries will be put into the snapshot.</p> <p>If the Leader was to send this Follower a 6th entry the follower will respond with a failure because it will not be able to get to the 5th entry and verify that the term in the 5th entry matches the prevLogTerm of the Leader.</p> <p>To fix this problem snapshotting should never clear all the entries from the in-memory journal. Atleast one (or more) entries need to be left there so that a more efficient previous entry comparison can be done.</p> <p>Operating System: All<br/> Platform: All</p> CONTROLLER-1067

Clustering : Removing all journal entries from a Followers in-memory journal causes Leader to send an InstallSnapshot

Bug Resolved Done Moiz Raja Moiz Raja Sat, 13 Dec 2014 04:51:11 +0000 Tue, 25 Jul 2023 08:23:50 +0000 Wed, 7 Jan 2015 14:26:19 +0000 mdsal 0 4 <p>Similarly if a follower was sent a snapshot with 0 unapplied entries present it is likely that it will require a further InstallSnapshot. Something must be done to prevent this situation as well.</p> <p>Rather than keeping a few entries in the follower journal even after snapshot, we can also check if the AE.previousLogIndex is &lt;= snapshotIndex. If yes, then we can assume that the previous index is part of the snapshot.</p> <p>Didnt get the 2nd comment. <br/> My understanding was that if a snapshot with 0 unapplied entries is applied, the snapshot index is set. In the AppendEntries Reply we do sent the lastIndex() which is the snapshotIndex (if the journal is empty).<br/> So we should be only getting appendentries, unless i am missing something very obvious.</p> <p>To ensure that the log is being replicated in the right order we need to check that,</p> <p>AE.prevLogIndex is present in the journal and that the journal.logEntry(prevLogIndex).term == AE.prevLogTerm.</p> <p>Just because a certain index is in the snapshot does not confirm that it matches the prev log entry that the leader has.</p> <p><a href="https://git.opendaylight.org/gerrit/#/c/13675/" class="external-link" target="_blank" rel="nofollow noopener">https://git.opendaylight.org/gerrit/#/c/13675/</a> - master</p> <p>To be cherry-picked to helium</p> <p><a href="https://git.opendaylight.org/gerrit/#/c/13940/" class="external-link" target="_blank" rel="nofollow noopener">https://git.opendaylight.org/gerrit/#/c/13940/</a> - helium</p> Development External issue ID 2509 External issue URL Issue Type ODL SR Target Milestone Rank 0|i02oa7: