Storage capacity units (SCUs) are subscription storage resource plans that can be used to offset the pay-as-you-go bills of various storage resources. Compared with disks purchased together with subscription Elastic Compute Service (ECS) instances or resource plans of a specific resource, SCUs offer a better combination of cost-effectiveness and flexibility together with pay-as-you-go resources.
Offset rules
SCUs can be used to offset the storage fees of multiple Alibaba Cloud storage services. The following table describes the rules that apply when you use SCUs to offset the storage fees of the snapshot service in regions in the Chinese mainland.
| Type | Offset factor | Description |
|---|---|---|
| Regular snapshot | 0.08 | Each GiB of regular snapshot storage consumes 0.08 GiB of an SCU. |
Offset order
You are charged based on the size and storage duration of snapshots. By default, the pay-as-you-go billing method is used. You can use Object Storage Service (OSS) storage plans or SCUs to offset the bills of snapshots and reduce costs. You are charged for a snapshot from the point in time when it is created to the point in time when it is released.
The storage fees of snapshots are offset based on the following order: SCUs > pay-as-you-go.
Examples
You stored snapshots that are 500 GiB in size in January 2022. You have purchased 35 GiB SCU. The following table describes the storage fees of snapshots calculated for the current month.
| Type | Offset by the SCU | Pay-as-you-go |
|---|---|---|
| Regular snapshot | 35 GiB SCU offsets the 437.5 GiB of snapshot storage. | You are charged for the remaining 62.5 GiB (500 GiB - 437.5 GiB) of snapshot storage on a pay-as-you-go basis. |