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Editorial Team
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Asked: 2026-05-25T23:39:05+00:00

I have a 4 node brisk cluster with 2 Cassandra nodes in Cassandra DC

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I have a 4 node brisk cluster with 2 Cassandra nodes in Cassandra DC and 2 brisk nodes in Brisk DC. I stress tested this set up using stress tool which is being shipped along with cassandra for 10 Million writes

On executing 

$ ./nodetool -h x.x.x.x compactionstats

pending tasks: 17
          compaction type        keyspace   column family bytes compacted     bytes total  progress
                    Major       Keyspace1       Standard1        45172473        60278166    74.94%

AFAIK major compaction is manually triggered from node tool. But I’m able to see that it has been triggered automatically.
Is this a desired behavior? If so what are all the situations this may occur?

Regards,
Tamil

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  1. Editorial Team

    From the doc:

    Compactions are triggered when at least N SStables have been flushed
    to disk, where N is tunable and defaults to 4.

    "Minor" compactions merge sstables of similar size; "major" compactions merge all sstables in a given ColumnFamily.

    Again from the doc:

    A major compaction is triggered either via nodeprobe, or automatically:

    Nodeprobe sends TreeRequest messages to all neighbors of the target
    node: when a node receives a TreeRequest, it will perform a readonly
    compaction to immediately validate the column family.

    Automatic compactions will also validate a column family and broadcast
    TreeResponses, but since TreeRequest messages are not sent to
    neighboring nodes, repairs will only occur if two nodes happen to
    perform automatic compactions within TREE_STORE_TIMEOUT of one
    another.

    You may find more info here and here

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