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Ephemeral nodes and cluster rebalancing

  • January 23, 2025
  • 1 reply
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dimitri_p
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In a cluster with k-safety=1, if I change one node to ephemeral, my understanding is that an automatic re-balance will be triggered and data from the ephemeral node will be distributed across the remaining nodes. But I have two questions:

  1. What happens if there are only two remaining nodes and they therefore can not sustain k-safety=1?
  2. Is it possible to prevent the re-balance operation from reading data from the ephemeral node?

Thank you!

    1 reply

    Nimmi_gupta
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    • Nimmi_gupta
    • Participating Frequently
    • March 3, 2025

    1.In a 3-node cluster, you cannot set a single node as ephemeral, it will result in an error.
    Hint: The cluster must have at least 2K+1 nodes. Use mark_design_ksafe(k) to lower K if needed.

    1. No, Its not possible to prevent the re-balance operation from reading data from the ephemeral node because when you plan to remove a node from your Vertica cluster, marking it as ephemeral tells Vertica to start redistributing data from that node to other nodes in the cluster to maintain data redundancy and avoid disruption when the node is finally removed.
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