Spot Instances and Spot Fleets Flashcards

1
Q

What is the maximum percent-off of on-demand pricing at which Spot Instances are offered?

A

Spot Instances are available at up to 90% off on-demand pricing.

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2
Q

What are some example use cases for Spot Instances?

A

​Think use cases where you don’t need persistent storage

  • Big Data
  • Containerized Workloads
  • CI/CD
  • Web Servers
  • HPC
  • Image & Media Rendering
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3
Q

Under default settings, what happens to your spot instance if, while you are using it, the spot price goes above your spot price maximum?

A

You have 2 minutes to choose whether to stop or terminate the instance

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4
Q

What is a Spot Block?

A

A Spot Block allows you to stop your spot instance from being terminated even if the spot price goes over your maximum spot price.

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5
Q

For how long is a Spot Block set?

A

Currently, Spot Blocks can be set for between 1 and 6 hours

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6
Q

Why are Spot Instances not useful for persistent workloads?

A

Becuase your spot instance capacity can be terminated at any time (if the price goes above your max spot price)

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7
Q

What is the difference between the two types of Request Types for Spot Instances?

A
  • For a one-time request type, when the spot price goes above and then back below your max, you don’t have your spot instance anymore
  • For a persistent request type, when the spot price goes above and then back below your max, a spot instance will be auto-restarted.

(More specifically, for a persistent request type, when the spot price goes above your max, it will resubmit your Spot Request)

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8
Q

What are the fields of a Spot Request?

A
  • Max Price
  • # of instances desired
  • Launch specs
  • Request type
  • Valid from & Valid until
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9
Q

What is a Spot Fleet?

A

A Spot Fleet is a collection of spot instances and, optionally, on-demand instances.

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10
Q

How does AWS select which types of instances are used to fill out your spot fleets?

A
  • You set up launch pools, and can define things like EC2 Instance Type, AZ, and OS
  • You can have multiple pools, and the fleet will choose the best way to implement depending on the strategy you define
  • Spot fleets stop launching instances once you reach your price threshold or desired capacity
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11
Q

How does your AWS Spot Fleet respond if one its Spot Instances is interrupted?

A
  • The Spot fleet attempts to maintain its target capacity fleet if your spot instances are interrupted.
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12
Q

When does AWS stop assigning new instances to your spot fleet?

A

Once you have reached your price threshold OR your desired capacity

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13
Q

What are the four types of spot fleet strategies?

A
  • capacityOptimized - come from pool with optimal capacity for number of instances launching (think trying to go for fewest interruptions)
  • lowestPrice - (default) Spot Instances are selected to come from the lowest price.
  • diversified - Spot Instances are selected to be distributed evenly across all spot pools
  • InstancePoolsToUseCount - used in conjunction with lowestprice, Spot Instances are selected to be distrubtuted evenly across a user-selected set of spot pools
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14
Q

What is a Spot Instance Pool?

A

A set of unused EC2 instances with the same instance type, operating system, Availability Zone, and network platform.

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15
Q

Why would you ever pick the capacityOptimized Spot Fleet Strategy over lowestPrice?

A
  • Capacity-optimized is better for workloads with a high cost of interruption.
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