Elastic Compute Service:What are preemptible instances?

Characteristics

The prices of preemptible instances can go much lower than other types of instances, but preemptible instances may be interrupted automatically.

Sharp fluctuations in prices

• The market prices of preemptible instances change with the supply and demand. Preemptible instances can be up to 90% cheaper than pay-as-you-go instances.

• Preemptible instances without a protection period cost less than those with a protection period, which lasts for one hour.

Note

The following figure shows the price difference between a pay-as-you-go instance and a preemptible instance that both use the ecs.hfg5.8xlarge instance type and reside in the China (Hangzhou) region. The prices are for reference only.

Automatic interruption and release

Preemptible instances may be interrupted and released by the system based on the market prices, instance resource inventory, maximum bidding prices when the instances are purchased, and the usage duration of the instances.

If Instance Usage Duration is set to One Hour when the preemptible instance was created, the system ensures that the instance runs for an hour without interruptions. When the one-hour period ends, the system compares the bidding price of the instance with the market price and checks the resource inventory to determine whether to release the instance.

• If the bidding price is equal to or higher than the market price and there is sufficient inventory, the instance continues to run as normal.

• If the bidding price is lower than the market price or the inventory is not enough, the system suspends the instance and notifies you that the instance will be released in five minutes.

  Note

  Bidding price: The bidding price is determined by the Highest Price per Instance parameter configured when you created the instance. It indicates the highest price you would like to pay for a preemptible instance, not the price based on which you are actually charged for the instance.

  • Use Automatic Bid: The bidding price always equals the market price.

  • Set Maximum Price: A fixed bidding price is set for each instance. Preemptible instances with higher bidding prices are more likely to be retained each time the system compares the bidding prices against market prices.

Scenarios

• Applicable scenarios

  Preemptible instances are suitable for business that runs in a stateless manner and is highly tolerant to faults and interruptions, such as:

  • Real-time analytics

  • Big data

  • Geological surveys

  • Image and media coding

  • Scientific computing

  • Scalable websites and web crawlers

  • Testing

• Inapplicable scenarios

  If your business needs to run for a long time and is highly sensitive to interruptions, preemptible instances are not recommended.

Limitations

• Preemptible instances may not be supported for your cloud servers. In this case, the option may not available when you create ECS instances.

• Preemptible instances cannot be converted to subscription instances.

• The instance types and bandwidths of preemptible instances cannot be changed.

• Preemptible instances do not support Internet Content Provider (ICP) filing.

Billing

The market prices of preemptible instances change with supply and demand. For information about the billing rules, see Billing of preemptible instances.

References

• Create a preemptible instance

• Query the interruption events of preemptible instances

• Stop a preemptible instance

• View the bills of a preemptible instance

• Restore data when a preemptible instance is reclaimed

FAQ

• What resources are covered by the price of a preemptible instance?

  The price of a preemptible instance covers only the instance types. Other resources such as disks and network bandwidths are billed at the same prices as those of pay-as-you-go instances.

• Am I notified when my preemptible instances are about to be released?

  Yes, the system sends you notifications when your preemptible instances are to be released. When your preemptible instance needs to be released due to a spot price change or insufficient resources, the instance enters the To Be Released state before it is automatically released in 5 minutes.

• Can I change the instance type of a preemptible instance?

  No, you cannot change the instance types preemptible instances.

• Which is cheaper, the preempible instances without a protection period or those with a protection period?

  Preemptible instances without a protection period are always cheaper than those with a one-hour protection period.

• Can I convert between preemptible instances with and without a protection period?

  No, protection periods cannot be enabled or disabled after preemptible instances are created. By default, preemptible instances have a one-hour protection period.

• Are non-protected preemptible instances more easily released than protected preemptible instances?

  You can check the release rate of each instance type on the instance buy page in the ECS console when you create preemptible instances with or without a protection period. Whether they are released by the system is determined by the supply and demand of instance types and bidding policies.

For more frequently asked questions about preemptible instances, see Instance FAQ.