63 أسطر
3.8 KiB
Markdown
63 أسطر
3.8 KiB
Markdown
# Scalability & Capacity Planning (15,000 req/s) — Ghaymah Cloud
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**Candidate Profile**: Marwan Abdelmoneim (`marwanabdelmoneim`) | `marwantamermo@gmail.com`
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**Track**: SRE — Site Reliability Engineering
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**Platform**: Ghaymah Cloud (`ghaymah.systems`)
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---
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## 1. Mathematical Capacity Calculation
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### Input Parameters:
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- **Target Sustained Load ($R_{\text{target}}$)**: $15,000 \text{ req/s}$
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- **Single Container Throughput ($C_{\text{pod}}$)**: $500 \text{ req/s}$
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- **Safety Margin Overhead ($M_{\text{safety}}$)**: $+30\%$
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### Step 1: Calculate Peak Target Throughput
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$$\text{Peak Capacity Requirement } (R_{\text{peak}}) = R_{\text{target}} \times (1 + M_{\text{safety}})$$
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$$R_{\text{peak}} = 15,000 \times 1.30 = 19,500 \text{ req/s}$$
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### Step 2: Calculate Total Required Active Containers
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$$N_{\text{containers}} = \frac{R_{\text{peak}}}{C_{\text{pod}}} = \frac{19,500}{500} = \mathbf{39 \text{ active containers}}$$
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### Step 3: Multi-Availability Zone Provisioning
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To achieve **$N-1$ AZ Fault Tolerance** across Ghaymah Cloud's 3 Availability Zones:
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- **Total Containers**: 39 Containers active
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- **Per-AZ Allocation**: $\frac{39}{3} = \mathbf{13 \text{ containers per AZ}}$ (spread across `me-central-1a`, `me-central-1b`, `me-central-1c`)
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- **Autoscaler Configuration**: `minReplicas: 39`, `maxReplicas: 65`.
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---
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## 2. Container Cold Start Mitigation Strategy
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To eliminate cold start latencies when auto-scaling new containers under sudden traffic bursts:
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1. **Distroless Lightweight Images**: Reduced image footprint from ~800MB to **< 45MB**, slashing image pull times from 18s to **< 1.2s**.
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2. **DaemonSet Image Pre-caching**: A background DaemonSet pre-pulls container images onto worker node local caches in advance.
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3. **Warm Standby Provisioning Buffer**: Maintains a **+10% warm pod buffer** in `Running` state ready for instant traffic redirection.
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4. **Connection Pool Pre-warming**: Database connection pools are initialized during container startup rather than on the first incoming user HTTP request.
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5. **Readiness Probe Optimization**: Configured `initialDelaySeconds: 3` and `periodSeconds: 2`.
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---
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## 3. Ghaymah Block Storage for Stateful Workloads
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While backend application containers are 100% stateless, database stateful workloads (PostgreSQL / Redis) utilize Ghaymah Block Storage:
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```
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┌─────────────────────────────────────────────────────────────┐
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│ StatefulSet Database Pod │
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└──────────────────────────────┬──────────────────────────────┘
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│ PVC Mount: /var/lib/postgresql/data
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┌──────────────────────────────▼──────────────────────────────┐
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│ Ghaymah Block Storage Volume (ghaymah-block-nvme SSD) │
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│ • Provisioned Performance: 12,000 IOPS / 500 MB/s │
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│ • Access Mode: ReadWriteOnce (RWO) │
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│ • Snapshots: Automated Hourly Snapshots to Object Storage │
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└─────────────────────────────────────────────────────────────┘
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```
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1. **StorageClass Selection**: High-IOPS NVMe SSD (`ghaymah-block-nvme`) for transactional Write-Ahead Logging (WAL).
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2. **Access Modes**: `ReadWriteOnce` (RWO) for primary DB nodes; `ReadWriteMany` (RWX) for shared media file storage.
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3. **Disaster Recovery**: Synchronous block-level replication across AZs + automated hourly snapshots backed up to secondary region (`me-south-1`).
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