# Force serial execution
testpilot test --concurrency 1 plans/
```

## Sharding (splitting the suite across workers)[​](#sharding-splitting-the-suite-across-workers "Direct link to Sharding (splitting the suite across workers)")

Sharding tells multiple independent processes or machines to each take a deterministic slice. You
specify it as `current/total` with a 1-based shard index:

```bash theme={null}