InsufficientInstanceCapacity

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Overview

When launching an EC2 instance on AWS, you might encounter an InsufficientInstanceCapacity error. This occurs when the specified instance type or availability zone (AZ) lacks sufficient capacity on AWS’s side.

Causes

The main reasons for this error are:

  1. Lack of capacity for a specific instance type
    • AWS provides EC2 instances based on physical servers in data centers. If a specific instance type (e.g., c5.large) is temporarily unavailable, launching it will fail.
  2. Availability zone (AZ) capacity limitations
    • Even within the same region, different AZs may have varying capacity, meaning certain zones may not allow instance launches.
  3. Reserved Capacity (RC) or Spot Instance restrictions
    • Some AZs prioritize Reserved Instances and Spot Instances over On-Demand instances, making it difficult to launch On-Demand instances.
  4. High AWS demand
    • Temporary surges in demand (such as Black Friday sales or large-scale machine learning jobs) can deplete capacity for specific instance types or AZs.

Solutions

To avoid this error, consider the following measures:

  1. Try a different availability zone (AZ)
    • If capacity is insufficient in one AZ, launching the instance in another AZ might work.
    • Be mindful of VPC settings and data transfer costs.
  2. Use a different instance type
    • If c5.large is unavailable, try c5.xlarge or c5d.large, which have similar specifications.
  3. Request a Spot Instance
    • If On-Demand instances are unavailable, Spot Instances may be an alternative solution.
  4. Use Capacity Reservation
    • Reserving capacity in advance ensures instance availability.
  5. Utilize Reserved Instances (RI)
    • Purchasing Reserved Instances secures specific instance types over an extended period, reducing the risk of capacity shortages.
  6. Try a different AWS region
    • Capacity varies by region, so launching the instance in another region might work.
  7. Contact AWS Support
    • If InsufficientInstanceCapacity errors persist, reaching out to AWS Support may provide additional solutions.

Conclusion

The InsufficientInstanceCapacity error occurs when AWS temporarily lacks resources for the requested instance type or AZ. To mitigate this, try different AZs, use alternative instance types, leverage capacity reservations, consider Spot Instances, or contact AWS Support for further assistance.