Tutorial / Cram Notes
Service quotas, also known as service limits, are the maximum number of resources you can create in an AWS account. Each AWS service has default quotas for resources like instances, volumes, and snapshots, which differ by region. These limits are designed to prevent excessive usage that could impact service performance.
Common AWS Service Quotas
Here are a few examples:
- Amazon EC2: Limits on the number of EC2 instances, EBS volumes, and Elastic IPs.
- Amazon S3: No limit on the amount of storage, but there is a limit on the rate at which you can store and retrieve data.
- Amazon VPC: Limits on the number of VPCs, subnets, and Internet gateways.
- AWS Lambda: Limits on the number of concurrent executions and the frequency of function invocations.
Why Service Quotas Matter
When planning for the AWS Certified Solutions Architect – Professional (SAP-C02) exam, understanding the service limits is crucial because designing highly available, scalable, and fault-tolerant systems often means deploying resources near or at the limits. Knowing how to request increases or how to architect solutions to stay within these limits is essential.
Best Practices with Service Quotas
- Proactively Request Increases: If you anticipate that your workload will exceed the default service quotas, it’s advisable to request increases well before you reach them.
- Monitoring Utilization: Using Amazon CloudWatch to monitor your service usage can help you manage your quotas effectively.
- Scalable Architectures: Design your architecture to scale horizontally rather than vertically, thus avoiding service limit issues.
Requesting Service Quotas Increases
If you need to operate beyond the default quotas, you can request a limit increase. This process typically involves:
- Navigating to the Service Quotas dashboard in the AWS Management Console.
- Selecting the service that you need an increase for.
- Requesting an increase for the specific quota.
AWS typically reviews your request and responds within a couple of business days. Some service limit increases may be granted automatically based on your usage history.
Example Scenarios
Scenario 1: Scaling EC2 Instances
Default limits on EC2 instances might restrict the number of instances you can launch. On the exam, you may encounter a scenario where you need to design an auto-scaling group that can scale to hundreds of instances. Knowing how to preemptively request an increase or design with smaller instance sizes to stay within the limits can be part of the solution.
Scenario 2: VPC Resources
For network-heavy architectures, staying within the VPC service quotas is vital. You might get a use case that requires more subnets than the default limit. Service quota knowledge will guide you in designing VPCs to either stay within the limits, use secondary CIDR blocks, or request increases where necessary.
Scenario 3: Lambda Functions
AWS limits the number of concurrent executions for Lambda functions. When designing serverless architectures, understanding these limits–and how to use features like AWS Step Functions to manage executions–is critical.
Conclusion
Having knowledge of AWS service quotas and how to navigate them plays a crucial role in designing systems on AWS. It’s critical for those preparing for the AWS Certified Solutions Architect – Professional exam to familiarize themselves with common service limits, how to monitor and manage them, as well as the process to request increases. Keep in mind that AWS might update these limits and the process for requesting increases, so always consult the latest AWS documentation during exam preparation.
Remember: Understanding service quotas is crucial, and knowledge of this area can make the difference between a successfully deployed cloud architecture and one that encounters unexpected limitations and hurdles.
Practice Test with Explanation
True or False: Service quotas in AWS are always the same across different regions.
- A) True
- B) False
Answer: B) False
Explanation: Service quotas can vary per region, as AWS sets different limits for resources across its global infrastructure to properly manage capacity and resources.
What is the default quota for running on-demand EC2 instances per region for new AWS accounts?
- A) 20
- B) 50
- C) 100
- D) 200
Answer: A) 20
Explanation: The default quota for running on-demand EC2 instances per region for new AWS accounts is typically 20, but it’s essential to check AWS documentation for the most up-to-date numbers as these can change.
True or False: Service quotas are adjustable, and users can request an increase if the default limits are insufficient for their needs.
- A) True
- B) False
Answer: A) True
Explanation: Service quotas can be increased upon request through the AWS Management Console or AWS Support. This involves submitting a service quota increase form for the specific resource you need to scale.
Multiple select: Which of the following services have their own set of quotas in AWS?
- A) Amazon S3
- B) AWS Lambda
- C) Amazon DynamoDB
- D) Amazon VPC
Answer: A) Amazon S3, B) AWS Lambda, C) Amazon DynamoDB, D) Amazon VPC
Explanation: All of the listed services have their own sets of quotas. Quotas may apply to aspects like the number of buckets for S3, the frequency and duration of Lambda function invocations, the number of read/write capacity units for DynamoDB, or the number of VPCs per region.
True or False: The quota for Elastic IP addresses is shared across all AWS regions.
- A) True
- B) False
Answer: B) False
Explanation: The quota for Elastic IP addresses is specific per AWS region; therefore, it’s not shared across all regions.
What is the primary purpose of AWS Trusted Advisor when considering service quotas?
- A) To optimize security settings
- B) To manage IAM roles and policies
- C) To monitor service limits and usage
- D) To troubleshoot network issues
Answer: C) To monitor service limits and usage
Explanation: The AWS Trusted Advisor checks include providing visibility into service usage and warnings when you approach service limits, thereby aiding in service quota management.
True or False: AWS service quotas can differ between AWS accounts based on the account’s service usage history and other factors.
- A) True
- B) False
Answer: A) True
Explanation: AWS might adjust service quotas based on an account’s usage history, performance needs, and other factors. Organizations with a history of extensive AWS use may have different limits compared to new accounts.
Which AWS service can be used to manage and monitor service quotas?
- A) AWS Cost Explorer
- B) AWS Service Health Dashboard
- C) AWS Service Quotas
- D) Amazon CloudWatch
Answer: C) AWS Service Quotas
Explanation: AWS Service Quotas is a service dedicated to managing and monitoring service quotas. It allows you to view current service quotas and request quota increases.
True or False: All AWS service quotas are hard limits and cannot be increased.
- A) True
- B) False
Answer: B) False
Explanation: While some service quotas are hard limits, many are soft limits that can be raised by submitting a request to AWS.
What is usually required to increase a service quota in AWS?
- A) A valid reason for the increase
- B) Approval from AWS Support
- C) A security assessment of the account
- D) A change in the pricing plan
Answer: B) Approval from AWS Support
Explanation: To increase most service quotas, users must submit a request and get approval from AWS Support, which typically evaluates the user needs and account status before approving an increase.
True or False: Unlimited mode on Amazon DynamoDB does not impose any read or write capacity limits on tables.
- A) True
- B) False
Answer: B) False
Explanation: Unlimited mode does not exist for Amazon DynamoDB. There is On-Demand and Provisioned capacity modes. On-Demand mode offers flexible billing and auto-scaling capabilities but still has other associated service quotas and limits.
Interview Questions
What is the purpose of service quotas in AWS Cloud services?
Service quotas, also known as service limits, are the maximum number of resources that you can create in an AWS account. Their purpose is to prevent over-provisioning of resources that can lead to unexpected costs and to ensure the availability and reliability of services by mitigating risks of resource exhaustion or system abuse.
How can you request an increase in a service quota for a specific AWS service?
You can request an increase in a service quota by using the Service Quotas console, the AWS Command Line Interface (CLI), or the AWS Service Quotas API. You need to navigate to the Service Quotas console, select the desired service, and then request a quota increase for the specific resource or operation that is currently limited.
Are service quotas always the same across all AWS regions?
No, service quotas can vary across different AWS regions. It’s essential to check the specific quotas for the region in which you are operating, as resource availability may differ due to demand and capacity variations in each region.
What is the default service quota for running On-Demand EC2 instances per AWS account per region?
The default service quota for running On-Demand EC2 instances is typically 20 instances per AWS account per region, but this can change over time. You should check the current limits using the AWS Service Quotas dashboard or the AWS documentation.
Can service quotas be managed and monitored automatically?
Yes, service quotas can be managed and monitored automatically using AWS Service Quotas and Amazon CloudWatch. You can create CloudWatch alarms to notify you when you are approaching a service quota limit, enabling proactive quota management and increase requests.
What is the difference between a service quota and an API rate limit in AWS?
A service quota is a limit on the quantity of resources you can provision within an AWS service, while an API rate limit is a restriction on the number of API requests that you can issue to an AWS service within a specific time period. Both are designed to ensure fair usage and stability of AWS services.
Is it possible to track historical changes to service quotas in AWS?
Yes, it is possible to track historical changes to service quotas using the AWS Service Quotas console. The Service Quotas console provides a history of your quota increase requests, including the requested values, status, and timestamps.
Can all AWS service quotas be increased, or are some hard limits that cannot be changed?
Most AWS service quotas can be increased upon request; however, some quotas are hard limits that cannot be changed due to technical constraints. These hard limits are typically set for the maximum allowable limit of a service to prevent abuse and ensure stability.
How do service quotas impact the design of a scalable and fault-tolerant architecture in AWS?
Service quotas impact the design of scalable and fault-tolerant architectures in AWS by requiring architects to be aware of the limits and to design systems that can work within those constraints or to plan for quota increases in advance of reaching them. This ensures that as the system scales or fails over, it will not be hindered by unexpected quota-related issues.
What strategy can be employed to ensure that service quotas do not become a bottleneck in a multi-tiered application’s deployment in AWS?
A strategy to prevent service quotas from becoming a bottleneck includes continuously monitoring service usage against the quotas, automating quota management with AWS Service Quotas, and incorporating scaling and load distribution mechanisms across multiple regions or availability zones to stay within quota limits while still meeting application demand.
Why is understanding the Elastic Load Balancer (ELB) service quotas important when designing highly available systems in AWS?
Understanding the ELB service quotas is essential when designing highly available systems because the number of ELBs, listeners, or target groups that can be created within an AWS account is limited. Overlooking these quotas may lead to an inability to deploy new ELBs when needed for scaling or failover, affecting the availability of the system.
What role does AWS Trusted Advisor play in managing service quotas?
AWS Trusted Advisor provides recommendations across various categories, one of which is service limits. It checks your usage against the service quotas and alerts you if you’re close to reaching one of those limits, allowing you to take action before any service is disrupted or a new resource cannot be provisioned due to a limit being reached.
Remember that AWS continually updates their services and features, including service quotas, so it’s vital to reference the latest AWS documentation or the AWS Service Quotas console for the most up-to-date information.
Great post on service quotas and limits! Very useful for the AWS Certified Solutions Architect – Professional exam.
Can someone explain the difference between soft and hard limits in AWS?
I appreciate the detailed explanation on IAM role limits. Thank you!
What’s the best way to monitor service quotas to avoid disruptions?
Very informative! Helped me a lot in my preparation.
This is good, but real-time examples would have made it better.
Anyone know the default limit for EC2 Instances per Region?
Thanks for the clear and concise information!