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Reserving compute capacity in advance to guarantee availability and improve cost predictability.
DESCRIPTION
Capacity reservation ensures that resources are available when needed, often in specific zones, reducing risk of shortages during spikes. Cloud providers offer reservations and commitments, trading flexibility for availability and discounts. It aids critical workloads, disaster recovery, and compliance with SLAs. Over-reservation wastes budget, while under-reservation risks capacity crunches. Organizations combine reservations with autoscaling and spot instances to balance cost and resilience.
ALTERNATIVE DEFINITIONS
AWS Documentation
On-Demand Capacity Reservations enable you to reserve capacity for your EC2 instances in a specific Availability Zone.
Emphasizes zone-specific reservation of EC2 capacity on demand.
Google Cloud
Committed use discounts (CUDs) provide discounted prices in exchange for a commitment to use a minimum level of resources for a specified term.
Focuses on cost commitments that ensure discounted capacity over time.
RELATED TERMS
Committed Use Discount Autoscaling Service Quotas SLA Compute Instances Availability Zone Burst Capacity Cost Optimization
COMPETING TERMS
On-Demand Instance Spot Instances
KNOWLEDGE AREAS
Cloud Infrastructure Data Services Platform & Tooling
TARGET AUDIENCE
Cloud Architect IT Manager DevOps Engineer Chief Technology Officer Solution Architect
EXTERNAL SOURCES
- Wikipedia - Cloud computing
- AWS - EC2 Capacity Reservations guide
- Microsoft Learn - Azure reservations overview
TOP QUESTIONS
What is capacity reservation in cloud computing?
It reserves compute resources ahead of time to guarantee availability and reduce price variability, often in specific availability zones.
Category: Definition
Why use capacity reservations?
They ensure critical workloads launch during demand spikes, meet SLAs, and can reduce costs via discounts compared to on-demand usage.
Category: Relevancy
What are common capacity reservation options?
AWS Capacity Reservations, Azure Reserved VM Instances, and Google Cloud committed use discounts are common approaches.
Category: Overview
What risks exist with capacity reservations?
Overcommitting wastes budget; undercommitting risks capacity shortages. Changing business needs can make reservations suboptimal.
Category: Risks
How are capacity reservations managed?
Track utilization, align reservations to predictable workloads, and periodically adjust commitments. Use monitoring and tagging for accountability.
Category: Management
How do reservations compare to on-demand and spot?
On-demand offers flexibility but higher cost; spot is cheaper but interruptible; reservations guarantee availability with discounts.
Category: Alternatives
What is currently a hot topic around capacity reservation?
Balancing reserved capacity with autoscaling and spot to optimize cost while ensuring reliability is a key strategy.
Category: Topic
How do I estimate reservation needs?
Analyze historical usage, forecast peaks, and consider multi-AZ distribution. Start with conservative commitments and iterate.
Category: Requirements
Can reservations be modified or canceled?
Policies vary by provider. Some allow exchanges or scope changes; others have fixed terms. Review provider documentation before committing.
Category: Opinion