AWS Certified Solutions Architect Pro – Study Notes Domain 2

Domain 2.0: Costing (5% of exam)

2.1 Demonstrate ability to make architectural decisions that minimize and optimize infrastructure cost

2.2 Apply the appropriate AWS account and billing set-up options based on scenario

2.3 Ability to compare and contrast the cost implications of different architectures

• EC2 types https://aws.amazon.com/ec2/
  • On-demand https://aws.amazon.com/ec2/pricing/on-demand/
    • Highest hourly rate, no commitments
    • Ideal for auto scaling groups and unpredictable workloads
    • Good for Dev/Test
  • Reserved: https://aws.amazon.com/ec2/pricing/reserved-instances/
    • Use cases:
      • Steady state, predictable usage
      • Apps that need reserved capacity
      • Upfront payments reduce hourly rate
    • Standard RI – get billed whether it’s powered on or off
      • Use this when you expect to run the server 24/7
      • 1 & 3 year contracts, 3 years cheapest
      • There is a marketplace to sell RIs https://aws.amazon.com/ec2/purchasing-options/reserved-instances/marketplace/
      • Payment options
        • All upfront (up to 68% off for 3-year term)
        • Partial upfront (up to 60% off for 3-year term)
        • No upfront (30% off for 1-year term)
    • Scheduled RI –
      • Use it when you need a set amount of instances for a particular time slice
      • Can only launch instances during that time slice
      • If you launch outside of that window, you are billed on-demand
      • Accrue charges hourly, but billed in monthly increments over term
      • 1 year term commitment
    • Convertible
      • Brand new, not on test yet
      • Up to 45% off
  • Spot https://aws.amazon.com/ec2/spot/pricing/
    • Cheapest
    • Flexible start and end times
    • Grid computing and HPC
    • Bidding type instance, if you are outbid:
      • Those instances drop with little notice
  • Dedicated (2 types): https://aws.amazon.com/ec2/dedicated-hosts/faqs/
    • Host (most expensive)
    • Instance (lose visibility into which host you are running on)
• Modifying your RIs http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ri-modifying.html
  • Can switch AZs within same region
  • Can change instance size within the same instance type
  • Instance type modifications are supported, but only for Linux… but not RHEL or SUSE
  • Cannot change instance size of Windows RIs
  • See normalization chart for calculating footprint to modify a non-convertible RI: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ri-modification-instancemove.html

    

• RDS RI’s https://aws.amazon.com/rds/reserved-instances/
  • RI Based on 5 criteria:
    • DB Engine
    • DB Instance Class
    • Deployment Type
    • License Model
    • Region
  • Any of these 5 items change, RDS reverts to On demand
• How to configure cross account access.
  • Create any custom policies 1^st
  • Create role with cross account access
  • Apply the policy to that role & note down the ARN
  • Grant access to the role
  • Switch to the role
  • https://aws.amazon.com/blogs/aws/new-cross-account-access-in-the-aws-management-console/
  • http://docs.aws.amazon.com/IAM/latest/UserGuide/tutorial_cross-account-with-roles.html
  • Why multiple AWS accounts?
    • Security
    • Billing
    • Growth through acquisition
• Consolidated billing http://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/consolidated-billing.html
  • Linked accounts that feed to one “Paying account” from 1 to 20 (or more with ticket) “Linked Accounts”
  • Paying account is independent & cannot access resources of linked accounts (and vice versa) by default
  • Easy to track charges and allocate costs
  • Get volume discounts on all your accounts
  • Unused reserve instances for EC2 are applied across the groups
  • CloudTrail is on a per account and per region basis but can be aggregated into 1 bucket in the paying account
• Tagging & Resource Groups
  • Great for sorting resources in a complex environment
  • Can sort by multiple tag keys (prod, dev, test, app, whatever)
  • By default, works within all regions, but can be filtered down to individual regions
  • By default, works with all services, but can also be filtered
  • Not all resource types support tagging, but you don’t need to know which for exam
• Budgets and CloudWatch Alarms
  • Used to track your current costs vs a set “budget” for a billing period
  • Updated every 24 hours
  • Does not show refunds
  • Not automatically created by AWS
  • Can be compared against AWS “estimated” costs to see how much budget is left over
  • Must create budgets on the Payee (in the event of a consolidate billing scenario) account
  • Can set alarms when you exceed actual or forecasted budgets, but you will still exceed.
    • It won’t stop chargeable services from running