orion/docs/architecture/capacity-planning.md

# Capacity Planning & Infrastructure Sizing

This document provides comprehensive capacity planning guidelines for the Wizamart platform, including resource requirements, scaling thresholds, and monitoring recommendations.

> **Related:** [Pricing Strategy](../marketing/pricing.md) for tier definitions and limits

---

## Tier Resource Allocations

Based on our [pricing tiers](../marketing/pricing.md), here are the expected resource requirements per client:

| Metric | Essential (€49) | Professional (€99) | Business (€199) | Enterprise (€399+) |
|--------|-----------------|--------------------|-----------------|--------------------|
| Products | 200 | 500 | 2,000 | Unlimited |
| Images per product | 3 | 5 | 8 | 10+ |
| Orders per month | 100 | 500 | 2,000 | Unlimited |
| SKU variants | 1.2x | 1.5x | 2x | 3x |
| Team members | 1 | 3 | 10 | Unlimited |
| API requests/day | 1,000 | 5,000 | 20,000 | Unlimited |

---

## Scale Projections

### Target: 1,000 Business Clients (€149/month tier)

This represents our primary growth target. Here's the infrastructure impact:

| Resource | Calculation | Total |
|----------|-------------|-------|
| **Products** | 1,000 clients × 500 products | **500,000** |
| **Product Translations** | 500,000 × 4 languages | **2,000,000 rows** |
| **Images (files)** | 500,000 × 5 images × 3 sizes | **7,500,000 files** |
| **Image Storage** | 7.5M files × 200KB avg | **1.5 TB** |
| **Database Size** | Products + translations + orders + indexes | **15-25 GB** |
| **Monthly Orders** | 1,000 clients × 300 orders | **300,000 orders** |
| **Order Items** | 300,000 × 2.5 avg items | **750,000 items/month** |
| **Monthly API Requests** | 1,000 × 10,000 req/day × 30 | **300M requests** |

### Multi-Tier Mix (Realistic Scenario)

More realistic distribution across tiers:

| Tier | Clients | Products Each | Total Products | Monthly Orders |
|------|---------|---------------|----------------|----------------|
| Essential | 500 | 100 | 50,000 | 50,000 |
| Professional | 300 | 300 | 90,000 | 150,000 |
| Business | 150 | 1,000 | 150,000 | 300,000 |
| Enterprise | 50 | 3,000 | 150,000 | 200,000 |
| **Total** | **1,000** | - | **440,000** | **700,000** |

---

## Server Sizing Recommendations

### Infrastructure Tiers

| Scale | Clients | vCPU | RAM | Storage | Database | Monthly Cost |
|-------|---------|------|-----|---------|----------|--------------|
| **Starter** | 1-50 | 2 | 4GB | 100GB SSD | SQLite | €20-40 |
| **Small** | 50-100 | 4 | 8GB | 250GB SSD | PostgreSQL | €60-100 |
| **Medium** | 100-300 | 4 | 16GB | 500GB SSD | PostgreSQL | €100-180 |
| **Large** | 300-500 | 8 | 32GB | 1TB SSD | PostgreSQL + Redis | €250-400 |
| **Scale** | 500-1000 | 16 | 64GB | 2TB SSD + CDN | PostgreSQL + Redis | €500-900 |
| **Enterprise** | 1000+ | 32+ | 128GB+ | 4TB+ + CDN | PostgreSQL cluster | €1,500+ |

### Recommended Configurations

#### Starter (1-50 clients)
```
Single Server Setup:
- Hetzner CX22 or similar (2 vCPU, 4GB RAM)
- 100GB SSD storage
- SQLite database
- nginx for static files + reverse proxy
- Estimated cost: €20-40/month
```

#### Small-Medium (50-300 clients)
```
Two-Server Setup:
- App Server: 4 vCPU, 8-16GB RAM
- Database: Managed PostgreSQL (basic tier)
- Storage: Local SSD + backup
- Optional: Redis for sessions/caching
- Estimated cost: €80-180/month
```

#### Large (300-1000 clients)
```
Multi-Component Setup:
- Load Balancer: nginx or cloud LB
- App Servers: 2-4 × (4 vCPU, 8GB RAM)
- Database: Managed PostgreSQL (production tier)
- Cache: Redis (managed or self-hosted)
- Storage: Object storage (S3-compatible) + CDN
- Estimated cost: €400-900/month
```

#### Enterprise (1000+ clients)
```
Full Production Setup:
- CDN: Cloudflare or similar
- Load Balancer: Cloud-native with health checks
- App Servers: 4-8 × (4 vCPU, 16GB RAM) with auto-scaling
- Database: PostgreSQL with read replicas
- Cache: Redis cluster
- Storage: S3 + CloudFront or equivalent
- Monitoring: Prometheus + Grafana
- Estimated cost: €1,500+/month
```

---

## Image Storage Architecture

### Capacity Calculations

| Image Size (optimized) | Files per 25GB | Files per 100GB | Files per 1TB |
|------------------------|----------------|-----------------|---------------|
| 100KB (thumbnails) | 250,000 | 1,000,000 | 10,000,000 |
| 200KB (web-ready) | 125,000 | 500,000 | 5,000,000 |
| 300KB (high quality) | 83,000 | 333,000 | 3,330,000 |
| 500KB (original) | 50,000 | 200,000 | 2,000,000 |

### Image Sizes Generated

Each uploaded image generates 3 variants:

| Variant | Dimensions | Typical Size | Use Case |
|---------|------------|--------------|----------|
| `thumb` | 200×200 | 10-20KB | List views, grids |
| `medium` | 800×800 | 80-150KB | Product cards, previews |
| `original` | As uploaded | 200-500KB | Detail views, zoom |

**Storage per product:** ~600KB (with 3 sizes for main image + 2 additional images)

### Directory Structure (Sharded)

To prevent filesystem performance degradation, images are stored in a sharded directory structure:

```
/uploads/
  └── products/
      ├── 00/                    # First 2 chars of hash
      │   ├── 1a/               # Next 2 chars
      │   │   ├── 001a2b3c_original.webp
      │   │   ├── 001a2b3c_800.webp
      │   │   └── 001a2b3c_200.webp
      │   └── 2b/
      │       └── ...
      ├── 01/
      └── ...
```

This structure ensures:
- Maximum ~256 subdirectories per level
- ~16 files per leaf directory at 1M total images
- Fast filesystem operations even at scale

### Performance Thresholds

| Files per Directory | Performance | Required Action |
|---------------------|-------------|-----------------|
| < 10,000 | Excellent | None |
| 10,000 - 100,000 | Good | Monitor, plan sharding |
| 100,000 - 500,000 | Degraded | **Implement sharding** |
| > 500,000 | Poor | **Migrate to object storage** |

---

## Database Performance

### Table Size Guidelines

| Table | Rows | Query Time | Status |
|-------|------|------------|--------|
| < 10,000 | < 1ms | Excellent |
| 10,000 - 100,000 | 1-10ms | Good |
| 100,000 - 1,000,000 | 10-50ms | **Add indexes, optimize queries** |
| 1,000,000 - 10,000,000 | 50-200ms | **Consider partitioning** |
| > 10,000,000 | Variable | **Sharding or dedicated DB** |

### Critical Indexes

Ensure these indexes exist at scale:

```sql
-- Products
CREATE INDEX idx_product_vendor_active ON products(vendor_id, is_active);
CREATE INDEX idx_product_gtin ON products(gtin);
CREATE INDEX idx_product_vendor_sku ON products(vendor_id, vendor_sku);

-- Orders
CREATE INDEX idx_order_vendor_status ON orders(vendor_id, status);
CREATE INDEX idx_order_created ON orders(created_at DESC);
CREATE INDEX idx_order_customer ON orders(customer_id);

-- Inventory
CREATE INDEX idx_inventory_product_location ON inventory(product_id, warehouse, bin_location);
CREATE INDEX idx_inventory_vendor ON inventory(vendor_id);
```

### Database Size Estimates

| Component | Size per 100K Products | Size per 1M Products |
|-----------|------------------------|----------------------|
| Products table | 100 MB | 1 GB |
| Translations (4 langs) | 400 MB | 4 GB |
| Orders (1 year) | 500 MB | 5 GB |
| Order items | 200 MB | 2 GB |
| Inventory | 50 MB | 500 MB |
| Indexes | 300 MB | 3 GB |
| **Total** | **~1.5 GB** | **~15 GB** |

---

## Bandwidth & Network

### Monthly Bandwidth Estimates (1000 clients)

| Traffic Type | Calculation | Monthly Volume |
|--------------|-------------|----------------|
| Image views | 500K products × 10 views × 500KB | **2.5 TB** |
| API requests | 10K req/client/day × 1000 × 30 × 2KB | **600 GB** |
| Static assets | CSS/JS cached, minimal | **50 GB** |
| **Total Egress** | | **~3 TB/month** |

### Bandwidth Costs (Approximate)

| Provider | First 1TB | Additional per TB |
|----------|-----------|-------------------|
| Hetzner | Included | €1/TB |
| AWS | $90 | $85/TB |
| DigitalOcean | 1TB free | $10/TB |
| Cloudflare | Unlimited (CDN) | Free |

**Recommendation:** Use Cloudflare for image CDN to eliminate egress costs.

---

## Scaling Triggers & Thresholds

### When to Scale Up

| Metric | Warning | Critical | Action |
|--------|---------|----------|--------|
| CPU Usage | > 70% avg | > 85% avg | Add app server |
| Memory Usage | > 75% | > 90% | Upgrade RAM or add server |
| Disk Usage | > 70% | > 85% | Expand storage |
| DB Query Time (p95) | > 100ms | > 500ms | Optimize queries, add indexes |
| API Response Time (p95) | > 500ms | > 2000ms | Scale horizontally |
| DB Connections | > 80% max | > 95% max | Add connection pooling |
| Error Rate | > 1% | > 5% | Investigate and fix |

### Architecture Transition Points

```
STARTER → SMALL (50 clients)
├── Trigger: SQLite becomes bottleneck
├── Action: Migrate to PostgreSQL
└── Cost increase: +€40-60/month

SMALL → MEDIUM (100 clients)
├── Trigger: Single server at 70%+ CPU
├── Action: Separate DB server
└── Cost increase: +€50-80/month

MEDIUM → LARGE (300 clients)
├── Trigger: Need for caching, higher availability
├── Action: Add Redis, consider multiple app servers
└── Cost increase: +€150-200/month

LARGE → SCALE (500 clients)
├── Trigger: Storage >500GB, high traffic
├── Action: Object storage + CDN, load balancing
└── Cost increase: +€200-400/month

SCALE → ENTERPRISE (1000+ clients)
├── Trigger: High availability requirements, SLA
├── Action: Full redundancy, read replicas, auto-scaling
└── Cost increase: +€600-1000/month
```

---

## Monitoring Requirements

### Essential Metrics

Track these metrics for capacity planning:

#### Infrastructure
- CPU utilization (per server)
- Memory utilization
- Disk I/O and usage
- Network throughput

#### Application
- Request latency (p50, p95, p99)
- Request rate (per endpoint)
- Error rate by type
- Active sessions

#### Database
- Query execution time
- Connection pool usage
- Table sizes
- Index usage

#### Business
- Active clients
- Products per client
- Orders per day
- API calls per client

### Monitoring Dashboard

The admin platform includes a **Capacity Monitoring** page at `/admin/platform-health` with:

1. **Current Usage** - Real-time resource utilization
2. **Growth Trends** - Historical charts for planning
3. **Threshold Alerts** - Warning and critical indicators
4. **Scaling Recommendations** - Automated suggestions

See [Platform Health Monitoring](#platform-health-monitoring) section below.

---

## Cost Analysis

### Infrastructure Cost per Client

| Scale | Clients | Monthly Infra | Cost/Client |
|-------|---------|---------------|-------------|
| Starter | 25 | €30 | €1.20 |
| Small | 75 | €80 | €1.07 |
| Medium | 200 | €150 | €0.75 |
| Large | 400 | €350 | €0.88 |
| Scale | 800 | €700 | €0.88 |
| Enterprise | 1500 | €1,800 | €1.20 |

### Revenue vs Infrastructure Cost

At 1,000 Business tier clients (€149/month):

| Item | Monthly |
|------|---------|
| **Revenue** | €149,000 |
| Infrastructure | €700-900 |
| Support (est.) | €3,000 |
| Development (est.) | €5,000 |
| **Gross Margin** | **~96%** |

---

## Disaster Recovery

### Backup Strategy by Scale

| Scale | Database Backup | File Backup | RTO | RPO |
|-------|----------------|-------------|-----|-----|
| Starter | Daily SQLite copy | Daily rsync | 4h | 24h |
| Small | Daily pg_dump | Daily sync | 2h | 12h |
| Medium | Managed backups | S3 versioning | 1h | 6h |
| Large | Point-in-time | S3 + cross-region | 30m | 1h |
| Enterprise | Streaming replicas | Multi-region | 5m | 5m |

---

## Platform Health Monitoring

The admin dashboard includes a dedicated capacity monitoring page that tracks:

### Metrics Displayed

1. **Client Growth**
   - Total active clients
   - New clients this month
   - Churn rate

2. **Resource Usage**
   - Total products across all vendors
   - Total images stored
   - Database size
   - Storage usage

3. **Performance Indicators**
   - Average API response time
   - Database query latency
   - Error rate

4. **Threshold Status**
   - Current infrastructure tier
   - Distance to next threshold
   - Recommended actions

### Alert Configuration

Configure alerts for proactive scaling:

```python
CAPACITY_THRESHOLDS = {
    "products_total": {
        "warning": 400_000,   # 80% of 500K
        "critical": 475_000,  # 95% of 500K
    },
    "storage_gb": {
        "warning": 800,       # 80% of 1TB
        "critical": 950,
    },
    "db_size_gb": {
        "warning": 20,
        "critical": 24,
    },
    "avg_response_ms": {
        "warning": 200,
        "critical": 500,
    },
}
```

---

## Quick Reference

### TL;DR Sizing Guide

| Clients | Server | RAM | Storage | Database | Monthly Cost |
|---------|--------|-----|---------|----------|--------------|
| 1-50 | 2 vCPU | 4GB | 100GB | SQLite | €30 |
| 50-100 | 4 vCPU | 8GB | 250GB | PostgreSQL | €80 |
| 100-300 | 4 vCPU | 16GB | 500GB | PostgreSQL | €150 |
| 300-500 | 8 vCPU | 32GB | 1TB | PostgreSQL + Redis | €350 |
| 500-1000 | 16 vCPU | 64GB | 2TB + CDN | PostgreSQL + Redis | €700 |
| 1000+ | 32+ vCPU | 128GB+ | 4TB+ + CDN | PostgreSQL cluster | €1,500+ |

### Key Formulas

```
Storage (GB) = (Products × Images × 3 sizes × 200KB) / 1,000,000
DB Size (GB) = Products × 0.00003 + Orders × 0.00002
Bandwidth (TB/mo) = Products × Daily Views × 500KB × 30 / 1,000,000,000
```

---

## See Also

- [Pricing Strategy](../marketing/pricing.md) - Tier definitions and limits
- [Multi-Tenant Architecture](multi-tenant.md) - How client isolation works
- [Background Tasks](background-tasks.md) - Task queue scaling
- [Production Deployment](../deployment/production.md) - Deployment guidelines