> ## Documentation Index > Fetch the complete documentation index at: https://docs.voicegateway.dev/llms.txt > Use this file to discover all available pages before exploring further. # Replay storage costs # Replay storage costs VoiceGateway's conversation replay captures every STT chunk, LLM token, TTS frame, and conversation-state snapshot for every session. This page surfaces the on-disk storage cost so the trade-off between fidelity and footprint is visible before you set per-project retention. ## What gets stored Four tables per the [migration 0004 schema](https://github.com/mahimailabs/voicegateway/blob/main/voicegateway/storage/migrations/0004_replay_tables.py): | Table | Row payload | Typical row size | | ------------------------ | ---------------------------------------------------------------------------------------------- | --------------------------------------------------- | | `replay_stt_events` | JSON: `text`, `is_final`, `alternatives` | 100 - 400 bytes | | `replay_llm_tokens` | JSON: `token_text`, `role`, `is_tool_invoke`, `tool_args_partial` | 80 - 200 bytes | | `replay_tts_frames` | JSON: `frame_duration_ms`, `underrun`, `voice_id` | 80 - 120 bytes | | `replay_state_snapshots` | JSON: `system_prompt`, `message_history`, `tool_call_in_flight`, `structured_output_collected` | 500 - 5000 bytes (depends on prompt + history size) | Every row also carries the boilerplate: `id`, `session_id`, `t_ms`, `provider`, `cost_usd`, `created_at`. Add roughly 80-120 bytes of column overhead per row. Indexes on `(session_id, t_ms)` add another 30-50% of payload size. ## Per-minute estimate For a typical voice conversation (caller speaks for half the time, agent for half, normal-cadence LLM with a 500-token system prompt): | Modality | Events per minute | Bytes per minute | | --------------------------- | ----------------- | ---------------- | | STT (partials + finals) | 30 - 60 | 8 KB - 24 KB | | LLM tokens | 200 - 500 | 30 KB - 80 KB | | TTS frames (20-50ms each) | 600 - 1500 | 60 KB - 180 KB | | State snapshots (1/sec cap) | 60 | 30 KB - 300 KB | **Total: roughly 130 KB - 580 KB per minute of conversation**, with the floor for short crisp exchanges and the ceiling for chatty agents with long conversation histories. The design target of 30-100 KB/min is achievable on the floor; realistic agents will land closer to the ceiling. If you find yourself trending above 500 KB/min consistently, the per-project `replay.enabled: false` toggle is the fastest mitigation. ## Worked example A solo developer running 100 voice calls per day, averaging 5 minutes each: ``` 100 calls/day × 5 min/call × 200 KB/min = 100,000 KB/day ≈ 100 MB/day ``` At the default 90-day retention: ``` 100 MB/day × 90 days ≈ 9 GB total replay storage ``` At AWS S3 standard storage prices (\~\$0.023/GB-month): ``` 9 GB × $0.023 ≈ $0.21/month ``` On the local SQLite database (no cloud markup), the cost is the disk byte cost: \~$0.01/GB-month on a developer SSD ≈ ~$0.09/month for the same 9 GB. A team agency running 10,000 conversations per day at 3 minutes average scales linearly: \~3 TB at 90-day retention, \~$70/month on S3 standard or ~$30/month on local disk. At that point the `retention_days` knob matters: dropping to 30 days cuts storage to one-third. ## Tuning knobs Three per-project knobs in `voicegw.yaml`'s `replay:` block influence storage: | Knob | Default | Effect | | -------------------- | ------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `enabled` | `true` | Capture for every session. Set `false` to skip capture entirely. | | `retention_days` | `90` | Age replay rows out after this window. Lower to reduce footprint linearly. | | `flush_size_events` | `500` | Batched writes; smaller writes more often, larger holds more memory. No storage effect. | | `buffer_size_events` | `5000` | In-memory cap. Above this, oldest events are dropped with a counter. The dashboard surfaces dropped events as "events dropped here" rather than silently misleading the developer. | The `enabled` toggle is the binary on/off. The `retention_days` knob is the gradient lever. The `buffer_size_events` and `flush_size_events` knobs trade off memory pressure and write batching but do not change long-term storage volume. ## Dashboard storage view `GET /api/replay/storage` returns per-project replay byte totals. The dashboard surfaces this as a breakdown so the developer sees the cost in real time: ```json theme={null} { "total_replay_size_bytes": 9234567890, "by_project": [ {"project": "acme", "replay_size_bytes": 8000000000}, {"project": "default", "replay_size_bytes": 1234567890} ] } ``` A future follow-up will surface this in a sidebar panel on the dashboard with cost-per-month estimates inline. ## Related * [Python SDK reference > Conversation replay capture](/api/python-sdk#conversation-replay-capture) * [Migration 0004 schema](https://github.com/mahimailabs/voicegateway/blob/main/voicegateway/storage/migrations/0004_replay_tables.py) * [`voicegw replay ` CLI signpost](/cli/replay)