High Availability and Scaling Flashcards
What goes into a Launch Template?
- AMI
- EC2 instance size
- Security groups
- Potentially networking information
What’s the most up to date and flexible way to create a reusable configuration for launching EC2 instances?
Launch templates. Launch configurations are the older version. It’s not wrong to use them, but when possible, use templates.
Is user data included in the Launch Template or Launch Configuration?
Yes
Advantages of Launch Templates
- Can be versioned. Configurations are immutable.
- Networking: Configurations don’t include networking information. Templates could.
For which services can be Auto Scaling configured?
Only for EC2
What can be done to reduce build times in EC2 instances?
Bake AMIs to reduce build times. You can avoid long provisioning times by putting everything in an AMI. This is better than using user data whenever possible.
Tips for improving Auto Scaling
- Spread out: Make sure you’re spreading your Auto Scaling groups over multiple AZs.
- Steady state groups: Allows us to create a situation where the failure of a legacy codebase or resource that can’t be scaled can automatically recover from failure.
- ELBs are essential Make sure you enable health checks from load balancers. Otherwise, instances, won’t be terminated and replaced when they fail health checks.
Options when scaling RDS?
- Read replicas
- Multi-AZ
- Careful with storage: RDS storage only scales up. It won’t scale back down.
- Vertical scaling is also an option
- Migrating to DynamoDB is also an option (in the exam)
- Aurora everything: Whenever possible, user Aurora if the situation calls for a relational advantage.
DynamoDB access patterns and pricing/scaling options
- Predictable: Provisioned
- Sporadic: On-demand
Can you switch pricing/scaling options in DynamoDB?
Yes, but only once per 24 hours per table
Cost vs Performance when scaling DynamoDB? (exam)
Keep cost in mind rather than performance when scaling DynamoDB
