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https://issues.apache.org/jira/browse/CASSANDRA-14679?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16597110#comment-16597110
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Dinesh Joshi commented on CASSANDRA-14679:
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If the operator misconfigures the node by removing a directory from
{{data_file_directories}}, I don't really think Cassandra can tell whether it
was intentional or unintentional. I think the best would be to store a small
file alongside {{cassandra.yaml}} on the node to remember state information.
That way when unexpected configuration changes do occur, the node knows about
them and stops the bootstrap process. If the disk / volume that had your
{{cassandra.yaml}} is inaccessible; should be a fatal error anyway and the node
won't start up.
It almost feels like Cassandra should dump key in-memory settings to a separate
file and compare them with the on-disk settings in {{cassandra.yaml}} on the
subsequent start up. Then we can have well defined set of rules to stop a
potentially problematic bootstrap. The only caveat being, many people don't
gracefully shutdown Cassandra.
> Prevent generating new tokens on a node when data exists
> --------------------------------------------------------
>
> Key: CASSANDRA-14679
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14679
> Project: Cassandra
> Issue Type: Bug
> Reporter: mck
> Priority: Critical
>
> Data loss is possible if a node starts up without {{system.local}} data
> available.
> If a node restarts and its {{system.local}} data is unavailable it will
> generate new tokens. This will cause range movements in the cluster causing
> potential data loss, as these range movements are not part of a
> bootstrap/decommission and leaves orphaned data around the cluster.
> This can happen if a node restarts without a JBOD entry available, or if the
> cassandra.yaml changes and leaves a JBOD entry out.
> If a node starts up, finds data but not its {{system.local}} it should not
> generate new tokens. Neither should it assign itself a new Host ID.
> This is described in more detail in
> http://thelastpickle.com/blog/2018/08/22/the-fine-print-when-using-multiple-data-directories.html
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