When to run anti-entropy repair
When to run anti-entropy repair is dependent on the characteristics of the cluster. General guidelines are presented here, and should be tailored to each particular case.
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An understanding of how repair works is required to fully understand the information presented on this page, see Anti-entropy repair. |
When is repair needed?
Run repair in these situations:
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Routinely to maintain node health.
Even if deletions never occur, schedule regular repairs. Setting a column to null is a delete.
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When recovering a node after a failure while bringing it back into the cluster.
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To update data on a node containing infrequently read data, and subsequently does not get read repair.
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To update data on a downed node.
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When recovering missing data or corrupted SSTables. You must run non-incremental repair.
Guidelines for running routine node repair
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Run full repairs weekly to monthly. Monthly is generally sufficient, but run more frequently if warranted.
Full repair is useful for maintaining data integrity, even if deletions never occur.
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Use the parallel and partitioner range options, unless precluded by the scope of the repair.
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Migrate off incremental repairs and then run a full repair to eliminate anti-compaction. Anti-compaction is the process of splitting an SSTable into two SSTables, one with repaired data and one with non-repaired data. This has compaction strategy implications.
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Run repair frequently enough that every node is repaired before reaching the time specified in the gc_grace_seconds setting. If this requirement is met, deleted data is properly handled in the cluster.
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Schedule routine node repair operations to minimize cluster disruption during low-usage hours and on one node at a time:
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Increase the time value setting of gc_grace_seconds if data is seldom deleted or overwritten. For these tables, changing the setting minimizes impact to disk space and provides a longer interval between repair operations.
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Mitigate heavy disk usage by configuring nodetool compaction throttling options (setcompactionthroughput and setcompactionthreshold) before running a repair.
Guideline for running repair on a downed node
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Do not use partitioner range,
-pr. -
Do not use incremental repair,
-inc.
