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Posted to commits@cassandra.apache.org by "Saranya Krishnakumar (Jira)" <ji...@apache.org> on 2022/11/07 19:09:00 UTC
[jira] [Comment Edited] (CASSANDRA-17870) nodetool/rebuild: Add flag to exclude nodes from local datacenter
[ https://issues.apache.org/jira/browse/CASSANDRA-17870?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17620650#comment-17620650 ]
Saranya Krishnakumar edited comment on CASSANDRA-17870 at 11/7/22 7:08 PM:
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[~yifanc] I created a PR as you had asked https://github.com/apache/cassandra/pull/1931
was (Author: saranya_k):
[~yifanc] created a PR [https://github.com/apache/cassandra/pull/1931 |https://github.com/apache/cassandra/pull/1931,]
> nodetool/rebuild: Add flag to exclude nodes from local datacenter
> -----------------------------------------------------------------
>
> Key: CASSANDRA-17870
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17870
> Project: Cassandra
> Issue Type: Improvement
> Components: Tool/nodetool
> Reporter: Saranya Krishnakumar
> Assignee: Saranya Krishnakumar
> Priority: Normal
> Attachments: fix_nodetool_rebuild.diff
>
> Time Spent: 40m
> Remaining Estimate: 0h
>
> During expansion by Dc, when we issue nodetool/rebuild from new dc to rebuild the data from other DCs. If src-dc is not passed explicitly, then C* tries to rebuild the data from the same (new dc) dc.
> We don’t exclude other nodes in the same DC. Only down sources and the local node itself are excluded.
> ```
> // We're _always_ filtering out a local node and down sources
> addSourceFilter(new RangeStreamer.FailureDetectorSourceFilter(failureDetector));
> addSourceFilter(new RangeStreamer.ExcludeLocalNodeFilter());
> ```
> We should fix nodetool/rebuild to exclude the local DC (from where we’re executing the command) while issuing nodetool/rebuild without passing src dc
>
> Example:
> in a 3 DC cluster,
> ks1 has DC1, DC2
> ks2 has DC1, DC2, DC3
> ks3 has DC2
> now, we add a new DC [DC4] and configured it to all 3 keyspaces.
> if we run rebuild with src DC as DC1, ks3 will fail as it does not have DC1.
> Now, without src DC, the expectation is rebuild would auto pick up DCs for each keyspace (let's say ks1: DC1, ks2: DC1, ks3: DC2) and would never fail due to under-replicated keyspaces.
> The issue with this approach (without src dc) is that, DC4 is getting picked up during rebuild (as src), but DC4 does not have any data yet!
> so, with the patch (ignore local dc flag), DC4 can be filtered out and let the database pick up the right dc for each keyspace [from existing 3 DCs].
> -- this is what is the expectation after the patch.
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