Quick Reference

Common Gemini commands and options for everyday use.

Basic Commands

# Standard test run (30 seconds)
./gemini --oracle-cluster=ORACLE_IP --test-cluster=TEST_IP

# Extended run with statement logging
./gemini \
  --oracle-cluster=ORACLE_IP \
  --test-cluster=TEST_IP \
  --duration=1h \
  --test-statement-log-file=test.json \
  --oracle-statement-log-file=oracle.json

# Stress test (no validation)
./gemini --test-cluster=TEST_IP --mode=write --duration=2h

# Read-only validation
./gemini --oracle-cluster=ORACLE_IP --test-cluster=TEST_IP --mode=read

Common Options

Option	Example	Description
--duration	1h, 30m, 24h	How long to run
--concurrency	10, 50, 100	Parallel workers
--mode	mixed, write, read	Operation mode
--seed	12345	Reproducible randomness
--schema-seed	67890	Reproducible schema
--fail-fast	(flag)	Stop on first error
--warmup	5m	Warmup period before validation

Statement Logging

# Enable statement logging for debugging
--test-statement-log-file=test.json
--oracle-statement-log-file=oracle.json

# With compression for long runs
--statement-log-file-compression=gzip

Schema Control

# Use custom schema
--schema=my_schema.json

# Generate specific schema size
--max-tables=3
--max-partition-keys=4
--max-clustering-keys=2
--max-columns=8

# Feature level
--cql-features=all  # basic, normal, all

Special Features

# Counter tables
--use-counters

# Lightweight transactions
--use-lwt

# Server-side timestamps
--use-server-timestamps

# Custom statement ratios
--statement-ratios='{"mutation":{"insert":0.8,"update":0.15,"delete":0.05}}'

Authentication

--test-username=user --test-password=pass
--oracle-username=user --oracle-password=pass

Timeouts

--request-timeout=30s
--connect-timeout=30s

Partition Distribution

# Distribution types
--partition-key-distribution=uniform  # Even distribution
--partition-key-distribution=zipf     # Hot spots (default)
--partition-key-distribution=normal   # Bell curve

# Partition count
--partition-count=2000000

Output

# Write results to file
--outfile=results.json

# Log level
--level=debug  # debug, info, warn, error

Docker

# Basic run
docker run -it scylladb/gemini:latest \
  --oracle-cluster=ORACLE_IP \
  --test-cluster=TEST_IP

# With mounted volume for logs
docker run -it \
  -v $(pwd)/logs:/logs \
  scylladb/gemini:latest \
  --oracle-cluster=ORACLE_IP \
  --test-cluster=TEST_IP \
  --test-statement-log-file=/logs/test.json

Reproducing a Run

When Gemini starts, it prints the seed values:

Seed:           12345678901234
Schema seed:    98765432109876

To reproduce:

./gemini \
  --seed=12345678901234 \
  --schema-seed=98765432109876 \
  --oracle-cluster=... \
  --test-cluster=...

Exit Codes

Code	Meaning
0	Success, no errors
1	Validation errors found
2	Configuration/startup error

Metrics

Prometheus metrics available at http://localhost:2112/metrics

Change bind address:

--bind=0.0.0.0:9090

Files Generated

File	Description
gemini.log	JSON application logs
test.json	Test cluster statement logs (if enabled)
oracle.json	Oracle cluster statement logs (if enabled)
ScyllaDB <ks>_logs	Statements stored in database