| name | managing-scylladb |
| description | Use when working with Scylladb — scyllaDB cluster management, shard-per-core
analysis, compaction strategy tuning, and CQL performance diagnostics. Covers
node health, tablet distribution, workload prioritization, repair scheduling,
and latency histogram analysis. Read this skill before any ScyllaDB
operations.
|
| connection_type | scylladb |
| preload | false |
ScyllaDB Management Skill
Monitor, analyze, and optimize ScyllaDB clusters safely.
MANDATORY: Discovery-First Pattern
Always check cluster status and list keyspaces before any CQL operations. Never assume keyspace or table names.
Phase 1: Discovery
#!/bin/bash
SCYLLA_HOST="${SCYLLADB_HOST:-localhost}"
SCYLLA_PORT="${SCYLLADB_PORT:-9042}"
echo "=== Cluster Status ==="
nodetool -h "$SCYLLA_HOST" status
echo ""
echo "=== Scylla Version ==="
nodetool -h "$SCYLLA_HOST" version
echo ""
echo "=== Keyspaces ==="
cqlsh "$SCYLLA_HOST" "$SCYLLA_PORT" -e "DESCRIBE KEYSPACES;"
echo ""
echo "=== Cluster Description ==="
nodetool -h "$SCYLLA_HOST" describecluster
echo ""
echo "=== Shard Info ==="
curl -s "http://$SCYLLA_HOST:10000/system/uptime_ms" 2>/dev/null
curl -s "http://$SCYLLA_HOST:10000/storage_service/hostid/local" 2>/dev/null
Phase 1 outputs: Node states, Scylla version, keyspace list, cluster topology, shard count.
Phase 2: Analysis
#!/bin/bash
SCYLLA_HOST="${SCYLLADB_HOST:-localhost}"
KEYSPACE="${1:-my_keyspace}"
echo "=== Keyspace Details ==="
cqlsh "$SCYLLA_HOST" -e "DESCRIBE KEYSPACE $KEYSPACE;"
echo ""
echo "=== Table Stats ==="
nodetool -h "$SCYLLA_HOST" tablestats "$KEYSPACE" | grep -E "Table:|Space used|Number of|Compaction|Read Latency|Write Latency" | head -30
echo ""
echo "=== Compaction Stats ==="
nodetool -h "$SCYLLA_HOST" compactionstats
echo ""
echo "=== Scheduling Groups (Workload Prioritization) ==="
curl -s "http://$SCYLLA_HOST:10000/task_manager/list_module_tasks/compaction" 2>/dev/null | head -10
echo ""
echo "=== Repair Status ==="
nodetool -h "$SCYLLA_HOST" repair_status 2>/dev/null || \
nodetool -h "$SCYLLA_HOST" netstats | grep -A5 "Repair"
echo ""
echo "=== Thread Pool Stats ==="
nodetool -h "$SCYLLA_HOST" tpstats | -25
Output Format
SCYLLADB ANALYSIS
=================
Cluster: [name] | Nodes: [count] | Version: [version]
Keyspaces: [count] | Shards/Node: [count]
ISSUES FOUND:
- [issue with affected keyspace/node]
RECOMMENDATIONS:
- [actionable recommendation]
Anti-Hallucination Rules
- NEVER assume resource names — always discover via CLI/API in Phase 1 before referencing in Phase 2.
- NEVER fabricate metric names or dimensions — verify against the service documentation or
--help output.
- NEVER mix CLI commands between service versions — confirm which version/API you are targeting.
- ALWAYS use the discovery → verify → analyze chain — every resource referenced must have been discovered first.
- ALWAYS handle empty results gracefully — an empty response is valid data, not an error to retry.
Counter-Rationalizations
| Shortcut | Counter | Why |
|---|
| "I'll skip discovery and check known resources" | Always run Phase 1 discovery first | Resource names change, new resources appear — assumed names cause errors |
| "The user only asked for a quick check" | Follow the full discovery → analysis flow | Quick checks miss critical issues; structured analysis catches silent failures |
| "Default configuration is probably fine" | Audit configuration explicitly | Defaults often leave logging, security, and optimization features disabled |
| "Metrics aren't needed for this" | Always check relevant metrics when available | API/CLI responses show current state; metrics reveal trends and intermittent issues |
| "I don't have access to that" | Try the command and report the actual error | Assumed permission failures prevent useful investigation; actual errors are informative |
