Cassandra operations

Install

emisar pack install fetches this pack, re-validates it, and verifies its content hash against the --hash below — the exact bytes this page was rendered against, so a tampered copy is rejected — before copying it into the runner's packs dir. The command reloads a running daemon itself; no manual restart.

sudo emisar pack install cassandra --hash sha256:67ba82c7ded40bb82a69c62ffb24f80b02132bf6523a56af95907df0d0f2ec2f

• cassandra.analyze_disk_pressure script low

  Analyze Cassandra disk pressure

  Runs a packaged shell script that inspects filesystem usage of the Cassandra data and commitlog directories. Read-only. Use as a first step when disk pressure is suspected. Output is human-readable; do not parse it.

  View source on GitHub
• cassandra.cqlsh_describe_keyspace exec low

  cqlsh -e "DESCRIBE KEYSPACE <ks>"

  Show the full DDL for one keyspace (tables, types, indexes, materialized views).

  View source on GitHub
• cassandra.cqlsh_describe_schema exec low

  cqlsh -e "DESCRIBE SCHEMA"

  Dump the full schema as CQL. Note: large clusters produce big output; rely on the byte cap.

  View source on GitHub
• cassandra.cqlsh_list_keyspaces exec low

  cqlsh -e "DESCRIBE KEYSPACES"

  List all keyspaces.

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• cassandra.cqlsh_list_roles exec low

  cqlsh -e "LIST ROLES"

  List all roles + their grants (requires CassandraAuthorizer/Authenticator).

  View source on GitHub
• cassandra.cqlsh_system_peers exec low

  SELECT * FROM system.peers_v2

  List the peer nodes as this coordinator sees them: dc, rack, schema version, tokens.

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• cassandra.cqlsh_system_size_estimates exec low

  SELECT * FROM system.size_estimates

  Show per-table partition + size estimates from the gossiped size_estimates table.

  View source on GitHub
• cassandra.nodetool_assassinate exec critical

  nodetool assassinate <address>

  Forcibly removes a dead node from gossip without streaming data. ONLY use when the node is permanently gone AND removenode failed. Risks: orphaned data, hint bleed, token misownership.

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• cassandra.nodetool_cleanup exec high

  nodetool cleanup [ks]

  Removes data no longer owned by this node (after a topology change). IO-heavy.

  View source on GitHub
• cassandra.nodetool_clearsnapshot exec high

  nodetool clearsnapshot -t <name>

  Deletes one snapshot tag from all keyspaces. Frees disk that was pinned by the snapshot.

  View source on GitHub
• cassandra.nodetool_compact exec high

  nodetool compact <ks> [table]

  Forces major compaction. For STCS this merges everything into one big SSTable — almost always a mistake. Prefer per-token-range compaction or letting the strategy run.

  View source on GitHub
• cassandra.nodetool_compactionhistory exec low

  nodetool compactionhistory

  List the last few compactions with bytes-in/out, duration, and dropped tombstones.

  View source on GitHub
• cassandra.nodetool_compactionstats exec low

  Cassandra compaction statistics

  Runs `nodetool compactionstats`. Pending compactions in the dozens-to-hundreds indicate the node is behind. Triggering repair on a node already behind on compactions usually makes things worse — wait for the queue to drain before recommending repair.

  View source on GitHub
• cassandra.nodetool_decommission exec critical

  nodetool decommission

  Streams this node's data to other replicas, then leaves the ring. NOT reversible without re-bootstrapping.

  View source on GitHub
• cassandra.nodetool_describecluster exec low

  nodetool describecluster

  Show the cluster name, partitioner, snitch, and schema versions per host. Schema disagreement here is a sign of partial DDL propagation.

  View source on GitHub
• cassandra.nodetool_describering exec low

  nodetool describering <keyspace>

  Show token range → replica endpoint mapping for one keyspace.

  View source on GitHub
• cassandra.nodetool_drain exec critical

  nodetool drain

  Stops accepting writes, flushes memtables, persists commit log positions. Node is unusable until restart.

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• cassandra.nodetool_failuredetector exec low

  nodetool failuredetector

  Show phi accrual failure detector scores per peer. Phi > 8 ≈ marked down.

  View source on GitHub
• cassandra.nodetool_flush exec high

  nodetool flush [ks] [table]

  Forces memtable → SSTable flush. Without args: all keyspaces. Brief IO spike + writeahead replay simplification.

  View source on GitHub
• cassandra.nodetool_getcompactionthroughput exec low

  nodetool getcompactionthroughput

  Show the current compaction throughput cap (MB/s; 0 = unlimited).

  View source on GitHub
• cassandra.nodetool_getconcurrentcompactors exec low

  nodetool getconcurrentcompactors

  Show the current concurrent_compactors setting.

  View source on GitHub
• cassandra.nodetool_getendpoints exec low

  nodetool getendpoints <ks> <table> <key>

  Show which replicas own a specific partition key. Use to confirm read/write routing.

  View source on GitHub
• cassandra.nodetool_getlogginglevels exec low

  nodetool getlogginglevels

  Show the current per-logger levels.

  View source on GitHub
• cassandra.nodetool_gossipinfo exec low

  nodetool gossipinfo

  Show per-peer gossip state — schema version, status, load, dc, rack, generation.

  View source on GitHub
• cassandra.nodetool_info exec low

  nodetool info

  Show this node: uptime, heap, load, exceptions, key+row+counter cache hit rates.

  View source on GitHub
• cassandra.nodetool_invalidatecountercache exec medium

  nodetool invalidatecountercache

  Drops the counter cache.

  View source on GitHub
• cassandra.nodetool_invalidatekeycache exec medium

  nodetool invalidatekeycache

  Drops the key cache. Reads pay cold-cache cost until it warms.

  View source on GitHub
• cassandra.nodetool_invalidaterowcache exec medium

  nodetool invalidaterowcache

  Drops the row cache.

  View source on GitHub
• cassandra.nodetool_listsnapshots exec low

  nodetool listsnapshots

  List all snapshots on this node with size + creation timestamp.

  View source on GitHub
• cassandra.nodetool_netstats exec low

  nodetool netstats

  Show streaming + read repair stats: completed/pending bytes, files transferred, pool stats.

  View source on GitHub
• cassandra.nodetool_proxyhistograms exec low

  nodetool proxyhistograms

  Show coordinator-side read/write latency histograms — what clients actually see.

  View source on GitHub
• cassandra.nodetool_rebuild exec high

  nodetool rebuild [source_dc]

  Re-bootstraps a node by streaming from another DC (or any DC if unspecified). Use after expanding into a new DC.

  View source on GitHub
• cassandra.nodetool_removenode exec critical

  nodetool removenode <host-id>

  Removes a down node from the cluster and streams its data from other replicas. Preferred over assassinate when there's quorum.

  View source on GitHub
• cassandra.nodetool_repair exec high

  Cassandra repair

  Wraps `nodetool repair`. The most dangerous "normal" operation — repair reconciles data between replicas, can take hours, produces significant cluster-wide load, may interact poorly with TTL/tombstone-heavy tables, and can worsen latency on every replica it touches. Always inspect ring status, compactions, disk, and logs first. Prefer mode=preview — a dry run that estimates the repair without performing it (requires Cassandra 4.0+) — before a real repair. Refuse to proceed if the ring has DN/UJ/UL/UM nodes.

  View source on GitHub
• cassandra.nodetool_ring exec low

  nodetool ring [keyspace]

  Show the token ring with owner host per token.

  View source on GitHub
• cassandra.nodetool_setcompactionthroughput exec medium

  nodetool setcompactionthroughput <MB/s>

  Sets max compaction throughput. 0 = unlimited (use carefully).

  View source on GitHub
• cassandra.nodetool_setlogginglevel exec medium

  nodetool setlogginglevel <logger> <level>

  Sets one logger's level. Use empty logger to reset all to the configured defaults.

  View source on GitHub
• cassandra.nodetool_snapshot exec medium

  nodetool snapshot -t <name> [ks]

  Atomic hard-link snapshot of SSTables. Cheap to take, expensive if left around.

  View source on GitHub
• cassandra.nodetool_status exec low

  Cassandra node ring status

  Runs `nodetool status`. Read-only — does not change Cassandra state. Use this before suggesting repair, cleanup, decommission, replacement, or topology changes. If any node is DN/UJ/UL/UM, do not recommend repair until the failure mode is understood.

  View source on GitHub
• cassandra.nodetool_stop_compaction exec high

  nodetool stop <operation>

  Stops in-flight operations of one type (COMPACTION, CLEANUP, VERIFY, etc).

  View source on GitHub
• cassandra.nodetool_tablehistograms exec low

  nodetool tablehistograms <ks> <table>

  Show local-node read/write/sstable/partition-size histograms for one table.

  View source on GitHub
• cassandra.nodetool_tablestats exec low

  Cassandra table stats

  Runs `nodetool tablestats`, optionally scoped to a single keyspace. Read-only. Output can be large for clusters with many tables. Use to identify tables with large sstable counts or large on-disk size — repairs on very large or tombstone-heavy tables are risky and worth surfacing before a repair recommendation.

  View source on GitHub
• cassandra.nodetool_tpstats exec low

  Cassandra thread pool stats

  Runs `nodetool tpstats` for active/pending/blocked counts per pool. High pending or blocked counts on MutationStage, CompactionExecutor, or ReadStage usually indicate ongoing pressure — investigate the cause before recommending operations that add load (repair, large reads, compaction tuning).

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• cassandra.nodetool_verify exec medium

  nodetool verify [ks] [table]

  Verifies SSTable checksums for one (or all) tables. Detects on-disk corruption.

  View source on GitHub
• cassandra.nodetool_version exec low

  nodetool version

  Show the Cassandra version string for the node.

  View source on GitHub