A preemptible (spot) RDS Custom instance offers the same performance as a regular RDS Custom instance at a price that varies in real-time according to market supply and demand. Compared with regular pay-as-you-go RDS Custom instances, preemptible (spot) instances can save up to 90% of your costs. This topic provides an overview of the features, limits, and billing information of preemptible (spot) instances.
Features
A preemptible (spot) instance is a pay-as-you-go instance whose resources are acquired by bidding. Compared with the fixed price of regular pay-as-you-go RDS Custom instances, the price of preemptible (spot) instances varies with the supply and demand of instance resources. This way, preemptible (spot) instances offers high discounts. However, a preemptible (spot) instance may be automatically interrupted and released when the available inventory resources for the instance are insufficient.
High discounts based on varying prices
Preemptible (spot) instances can save up to 90% of your costs compared with regular RDS Custom pay-as-you-go instances based its varying price.
The following figure compares the costs of a regular RDS Custom instance and a preemptible (spot) RDS Custom instance. The two instances use the same instance type (rds.ns8.8xlarge.8cm) and are both located in the China (Hangzhou) region. The prices shown in the figure are for reference only and those displayed on the buy page shall prevail.
Automatic interruption and release
A preemptible (spot) instance is automatically interrupted and changes to the pending release state when the available inventory resources for the instance are insufficient. In this case, a notification is sent to the instance owner and the instance is released after five minutes.
Limits
Preemptible (spot) instances support only the AI Node architecture and can use only cloud disks.
Preemptible (spot) instances cannot be converted to subscription instances.
The specifications of preemptible (spot) instances cannot be changed.
Billing cycle
You are charged for preemptible (spot) instances by second using the pay-as-you-go method. The bills are generated on an hourly basis.
Billing formula
Instance price: The instance price indicates only the price for the instance type. The costs of additional resources such as disks and Internet bandwidth are not included.
Market price: The market price of the instance varies with the supply and demand of instance resources.
Billing duration: The billing duration of an instance indicates the duration from the instance creation time to the instance release time, which can be divided into multiple periods with different market prices.
Instance price | Billing formula |
The real-time market price during each period | ΣReal-time market price in each period × Period during which the market price lasts |
Create a preemptible (spot) instance
To create a preemptible (spot) instance, configure specific parameters to the values described in the following table when you create an RDS Custom instance. For more information, see Create an RDS Custom instance.
Parameter | Description |
Billing Method | Select Pay-as-you-go. |
Mode | Select Bidding. |
Maximum Unit Price of Instance | Select Automatic Bidding. Currently, only Automatic Bidding is available for this parameter. Selecting this value indicates that you always accept the real-time market price as the billing price for the instance type. |