Implementing Capacity Planning
Let’s explore how to implement capacity planning in practice.
Capacity Planning Process
A structured capacity planning process includes:
-
Data Collection
- Gather historical usage data
- Collect business projections
- Document system dependencies
- Measure resource consumption
-
Analysis and Forecasting
- Identify trends and patterns
- Generate demand forecasts
- Model resource requirements
- Create capacity plans
-
Implementation
- Provision resources according to plan
- Configure auto-scaling policies
- Implement capacity alerts
- Document capacity decisions
-
Monitoring and Adjustment
- Track actual vs. forecast usage
- Measure forecast accuracy
- Adjust models based on observations
- Update capacity plans regularly
Capacity Planning Tools
Several tools can assist with capacity planning:
-
Monitoring Systems
- Prometheus + Grafana
- Datadog
- New Relic
- Dynatrace
-
Forecasting Tools
- Prophet (Facebook)
- StatsModels (Python)
- TensorFlow Time Series
- Amazon Forecast
-
Resource Modeling
- Custom simulation tools
- Queueing calculators
- Load testing frameworks (JMeter, Locust)
- Cloud provider calculators
-
Capacity Management
- Kubernetes Cluster Autoscaler
- AWS Auto Scaling
- Terraform for infrastructure as code
- Custom capacity management systems
Example: Capacity Planning for a Web Service
Let’s walk through a capacity planning example for a web service:
Step 1: Collect and analyze historical data
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
from statsmodels.tsa.seasonal import seasonal_decompose
# Load historical data
data = pd.read_csv('request_data.csv', parse_dates=['timestamp'])
data.set_index('timestamp', inplace=True)
# Resample to hourly data
hourly_data = data['requests'].resample('H').sum()
# Analyze seasonality
result = seasonal_decompose(hourly_data, model='multiplicative', period=24*7) # Weekly seasonality
# Plot components
fig, (ax1, ax2, ax3, ax4) = plt.subplots(4, 1, figsize=(12, 10))
result.observed.plot(ax=ax1, title='Observed')
result.trend.plot(ax=ax2, title='Trend')
result.seasonal.plot(ax=ax3, title='Seasonality')
result.resid.plot(ax=ax4, title='Residuals')
plt.tight_layout()
plt.savefig('seasonality_analysis.png')
Step 2: Forecast future demand
from fbprophet import Prophet
# Prepare data for Prophet
prophet_data = pd.DataFrame({
'ds': hourly_data.index,
'y': hourly_data.values
})
# Create and fit model
model = Prophet(
yearly_seasonality=True,
weekly_seasonality=True,
daily_seasonality=True,
changepoint_prior_scale=0.05
)
model.fit(prophet_data)
# Make future dataframe
future = model.make_future_dataframe(periods=24*30, freq='H') # Forecast 30 days
# Forecast
forecast = model.predict(future)
# Plot forecast
fig = model.plot(forecast)
plt.title('Request Forecast')
plt.ylabel('Requests per Hour')
plt.savefig('request_forecast.png')
# Extract peak forecast
peak_forecast = forecast['yhat_upper'].max()
Step 3: Model resource requirements
# Resource requirements per request (from load testing)
resources_per_request = {
'cpu_cores': 0.0002, # CPU cores per request
'memory_mb': 0.5, # MB of memory per request
'disk_iops': 0.01, # Disk IOPS per request
'network_mbps': 0.005 # Mbps per request
}
# Calculate resource needs for peak forecast
peak_resources = {
'cpu_cores': peak_forecast * resources_per_request['cpu_cores'],
'memory_mb': peak_forecast * resources_per_request['memory_mb'],
'disk_iops': peak_forecast * resources_per_request['disk_iops'],
'network_mbps': peak_forecast * resources_per_request['network_mbps']
}
# Add headroom (50%)
headroom_factor = 1.5
capacity_plan = {k: v * headroom_factor for k, v in peak_resources.items()}
print("Capacity Plan:")
for resource, amount in capacity_plan.items():
print(f"- {resource}: {amount:.2f}")
Step 4: Translate to infrastructure
# Instance types and their resources
instance_types = {
'small': {
'cpu_cores': 2,
'memory_mb': 4096,
'cost_per_hour': 0.05
},
'medium': {
'cpu_cores': 4,
'memory_mb': 8192,
'cost_per_hour': 0.10
},
'large': {
'cpu_cores': 8,
'memory_mb': 16384,
'cost_per_hour': 0.20
}
}
# Calculate instances needed
def calculate_instances(capacity_plan, instance_type):
specs = instance_types[instance_type]
cpu_instances = math.ceil(capacity_plan['cpu_cores'] / specs['cpu_cores'])
memory_instances = math.ceil(capacity_plan['memory_mb'] / specs['memory_mb'])
return max(cpu_instances, memory_instances)
# Calculate for each instance type
instance_counts = {
instance_type: calculate_instances(capacity_plan, instance_type)
for instance_type in instance_types
}
# Calculate costs
instance_costs = {
instance_type: count * instance_types[instance_type]['cost_per_hour'] * 24 * 30
for instance_type, count in instance_counts.items()
}
# Find most cost-effective option
most_cost_effective = min(instance_costs, key=instance_costs.get)
print(f"Most cost-effective option: {instance_counts[most_cost_effective]} {most_cost_effective} instances")
print(f"Monthly cost: ${instance_costs[most_cost_effective]:.2f}")
Step 5: Implement capacity plan
# Kubernetes deployment with HPA
apiVersion: apps/v1
kind: Deployment
metadata:
name: web-service
spec:
replicas: 10 # Initial capacity
selector:
matchLabels:
app: web-service
template:
metadata:
labels:
app: web-service
spec:
containers:
- name: web-service
image: web-service:1.0.0
resources:
requests:
cpu: "500m"
memory: "512Mi"
limits:
cpu: "1000m"
memory: "1Gi"
---
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
name: web-service-hpa
spec:
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: web-service
minReplicas: 5
maxReplicas: 50
metrics:
- type: Resource
resource:
name: cpu
target:
type: Utilization
averageUtilization: 70
- type: Resource
resource:
name: memory
target:
type: Utilization
averageUtilization: 80
Advanced Capacity Planning Strategies
As your systems mature, consider these advanced strategies:
Multi-Region Capacity Planning
Planning capacity across multiple regions requires additional considerations:
- Regional Traffic Distribution: How traffic is distributed geographically
- Failover Scenarios: Capacity needed during regional failures
- Data Replication: Impact of data synchronization on capacity
- Latency Requirements: How latency affects regional deployment
Example Multi-Region Capacity Plan:
regions:
us-east:
normal_traffic_percentage: 40
peak_rps: 5000
instances:
baseline: 20
peak: 30
failover: 50 # Can handle us-west failure
us-west:
normal_traffic_percentage: 30
peak_rps: 3750
instances:
baseline: 15
peak: 25
failover: 45 # Can handle us-east failure
eu-central:
normal_traffic_percentage: 20
peak_rps: 2500
instances:
baseline: 10
peak: 15
failover: 20 # Not a failover region
ap-southeast:
normal_traffic_percentage: 10
peak_rps: 1250
instances:
baseline: 5
peak: 10
failover: 15 # Not a failover region