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Cassandra

Learn how the Cassandra integration connects with Netdata and how to configure it.

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Cassandra Operations Guides

Practical guides for running, troubleshooting, and monitoring Apache Cassandra in production.

Cassandra Operations Guides 32 pages

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Cassandra Batch Too Large Warning: How To Fix It

Diagnose and remediate Cassandra batch size warnings and coordinator OOM caused by oversized multi-partition batches.

Cassandra Commit Log Disk Full: How To Fix It

Troubleshoot and recover when Cassandra commitlog segment exhaustion forces memtable flushes, overwhelms the write path, and blocks mutations.

Cassandra commitlog pending tasks: write-path I/O pressure

Diagnose and resolve sustained CommitLog PendingTasks in Apache Cassandra, where commitlog fsync bottlenecks delay write acknowledgments and cascade into dropped mutations.

Cassandra compaction death spiral: when writes outrun compaction throughput

Diagnose and recover from Cassandra compaction backlog when write rates exceed compaction throughput, causing SSTable accumulation, read amplification, and disk saturation.

Cassandra compaction strategies: STCS vs LCS vs TWCS vs UCS

Choose and operate the right Cassandra compaction strategy by understanding the I/O, space, and read amplification tradeoffs between STCS, LCS, TWCS, and UCS.

Cassandra disk space exhaustion: emergency recovery when the data volume fills

Emergency runbook for recovering a Cassandra node when disk space is exhausted, compaction stalls, and writes are rejected.

Cassandra dropped mutations: silent write loss and load shedding

Diagnose and recover from Cassandra dropped mutations, where replicas silently discard writes past queue timeout, causing silent data loss and consistency gaps.

Cassandra dropped reads and other messages: reading nodetool tpstats Dropped

Interpret nodetool tpstats Dropped counters, correlate message types with thread pool saturation, and understand what each scope means for reads, writes, hints, and repairs.

Cassandra GC death spiral: long pauses, gossip flapping, and recovery

Operational guide to identifying, diagnosing, and recovering from Cassandra GC death spirals caused by heap pressure, gossip timeouts, and hint replay floods.

Cassandra GC pauses too long: diagnosing G1 stop-the-world pauses

Diagnose and resolve long G1 stop-the-world pauses in Cassandra before they trigger gossip failures and client timeouts.

Cassandra gossip flapping: nodes bouncing UP and DOWN

Diagnose and stop Cassandra nodes flapping between UP and DOWN states caused by GC pressure, network issues, or gossip saturation.

Cassandra heap pressure: sizing the JVM heap and tuning G1GC

Size the JVM heap and tune G1GC for Cassandra 4.x and 5.x to avoid GC pauses, gossip flapping, and the death spiral.

Cassandra hint overflow: max_hint_window expiry and silent data divergence

Diagnose and recover from Cassandra hint window expiration, hint accumulation, and the silent data divergence that follows extended replica outages.

Cassandra hints accumulating: hinted handoff backlog and replay storms

Diagnose and resolve Cassandra hinted handoff backlog and replay storms before coordinator disk exhaustion and cascading replica failures.

Cassandra hot partition: when one key saturates a replica set

Diagnose and mitigate hot partitions in Apache Cassandra when a single key concentrates traffic, saturating replicas and spiking tail latency.

Cassandra java.lang.OutOfMemoryError: Java heap space - causes and recovery

Diagnose and recover from Cassandra java.lang.OutOfMemoryError: Java heap space with heap sizing guidance, partition and batch analysis, and GC tuning.

Cassandra killed by the Linux OOM killer: off-heap memory and RSS

Diagnose and prevent Linux OOM kills on Cassandra nodes when off-heap RSS exceeds available RAM despite a healthy JVM heap.

Cassandra large partition pathology: Compacting large partition warnings and reads

Diagnose and fix Cassandra large partitions when you see Compacting large partition warnings, read latency spikes, and JVM heap pressure.

Cassandra monitoring checklist: the signals every production cluster needs

A tiered checklist of Cassandra monitoring signals, from survival-level liveness checks to expert-level composite alerting patterns.

Cassandra native transport not running: node UP in gossip but refusing CQL clients

Diagnose why a Cassandra node shows UN in gossip but refuses CQL client connections, and restore native transport safely.

Cassandra node showing DN in nodetool status: gossip, phi, and recovery

Diagnose why Cassandra nodes appear as DN in nodetool status, understand phi accrual failure detection, and recover from gossip flapping and network partitions.

Cassandra Not enough space for compaction: STCS space amplification and recovery

Operational guide to diagnosing and recovering from Cassandra disk space exhaustion caused by STCS compaction space amplification, including per-strategy headroom and emergency remediation.

Cassandra OperationTimedOutException: client-side timeouts vs server timeouts

Distinguish client-side driver timeouts from server-side ReadTimeout and WriteTimeout in Cassandra, correlate the right signals, and turn the correct knob.

Cassandra pending compactions growing: the compaction backlog runbook

Diagnose and recover from growing Cassandra compaction backlogs before read latency and disk space spiral out of control.

Cassandra ReadTimeoutException: diagnosing coordinator read timeouts

Diagnose server-side Cassandra read timeouts where the coordinator fails to gather enough replica responses within read_request_timeout_in_ms.

Cassandra repair not running: the silent gap that resurrects deleted data

Detect when Cassandra anti-entropy repair stalls, diagnose why repair fails to complete within gc_grace_seconds, and prevent silent tombstone resurrection.

Cassandra Scanned over N tombstones warning: finding the offending query

Diagnose Cassandra tombstone warnings by identifying the table, partition, and query behind excessive tombstone scans before reads abort or trigger GC pressure.

Cassandra TombstoneOverwhelmingException: reads aborted by tombstone_failure_threshold

Operational guide to diagnosing and fixing Cassandra reads aborted by tombstone_failure_threshold, including per-table diagnosis, compaction, and repair correlation.

Cassandra Too many open files: file descriptor exhaustion

Diagnose and resolve file descriptor exhaustion in Apache Cassandra, including ulimit tuning, SSTable growth, and connection leak detection.

Cassandra too many SSTables per table: read amplification and how to fix it

Fix high SSTable counts in Cassandra before read amplification crushes latency. Diagnosis, emergency compaction, and root-cause remediation for LCS and STCS.

Cassandra UnavailableException: not enough replicas for the consistency level

Diagnose and recover from Cassandra UnavailableException when the coordinator cannot satisfy the requested consistency level due to insufficient live replicas.

Cassandra zombie data resurrection: gc_grace_seconds and unrepaired tombstones

Deleted data reappears when tombstones expire before repair reconciles them across replicas. Detect the silent failure and recover safely.

Academy

Cassandra Monitoring

Learn everything about monitoring & troubleshooting Cassandra, what metrics are important to monitor and why, and how to monitor Cassandra with Netdata.

Resources

Best Cassandra Monitoring Tools: 10 Ranked (2026)

We ranked 10 Cassandra monitoring tools on JMX metric depth, collection resolution, alerting, and pricing predictability so you pick the right fit.

Blog

Release 1.37: Infinite Scalability & Database Tiering

Continuing to Innovate and Improve with New Release Features

Monitoring & troubleshooting Cassandra with Netdata

Comprehensive Tools for Effective Database Management

Cassandra Monitoring: Key Metrics & Best Practices

Strategies For Ensuring Peak Performance & Stability