Allow nodetool cms reconfigure to ignore specific hosts - #5084
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nvharikrishna wants to merge 1 commit into
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Allow nodetool cms reconfigure to ignore specific hosts#5084nvharikrishna wants to merge 1 commit into
nvharikrishna wants to merge 1 commit into
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Add a --ignore option to nodetool cms reconfigure. Hosts given to it are excluded from the new CMS, on top of any nodes that are already down. This helps when shrinking a cluster. Today, decommissioning a CMS member hands that role to another node which may itself be due for decommission, so the CMS has to be reconfigured again and again. Excluding the departing nodes up front keeps CMS membership stable for the whole shrink, because decommissioning a node that is not a CMS member does not trigger a reconfiguration. The ignore list applies to that one command only. It is not stored, so cms describe still reports whether the CMS matches the nodes currently in the cluster. patch by nvharikrishna; reviewed by <Reviewers> for CASSANDRA-21627
smiklosovic
reviewed
Aug 31, 2026
| description = "Hosts to exclude from the new CMS, in addition to any which are currently down. Useful " + | ||
| "before shrinking a cluster: excluding the nodes which are about to be decommissioned " + | ||
| "keeps the CMS membership stable, avoiding a reconfiguration per decommissioned member.") | ||
| private List<String> ignoredEndpoints = new ArrayList<>(); |
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it would be (maybe) cool if this was accepting CIDR / whole subnets. This would basically ignore whole set of nodes instead of enumerating them one by one.
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--ignoreoption tonodetool cms reconfigure. Hosts given to it are excluded from the new CMS, on top of any nodes that are already down.This helps when shrinking a cluster. Today, decommissioning a CMS member hands that role to another node which may itself be due for decommission, so the CMS has to be reconfigured again and again. Excluding the departing nodes up front keeps CMS membership stable for the whole shrink, because decommissioning a node that is not a CMS member does not trigger a reconfiguration.
The ignore list applies to that one command only. It is not stored, so cms describe still reports whether the CMS matches the nodes currently in the cluster.
patch by nvharikrishna; reviewed by for CASSANDRA-21627
CASSANDRA-21627