A storage capacity unit (SCU) is a type of subscription billing method. You can purchase multiple SCUs and use them to offset the pay-as-you-go bills of multiple Alibaba Cloud storage services.
Purchase SCUs
For more information about how to purchase SCUs, see Create an SCU.
Offset rules
SCUs can be used to offset the storage usage fees of various Alibaba Cloud storage services. The following table describes the offset coefficients when you use SCUs to offset the storage usage fees of each type of NAS file system in regions in the Chinese mainland.
For more information about the offset coefficients for other Alibaba Cloud storage services and in other regions, see Pricing.
File system type | Offset coefficient | Description |
Capacity NAS file system | 0.25 | You can use 0.25 GiB of capacity in your SCU to offset the storage usage fee of 1 GiB for a Capacity NAS file system. |
Performance NAS file system | 0.89 | You can use 0.89 GiB of capacity in your SCU to offset the storage usage fee of 1 GiB for a Performance NAS file system. |
Offset order
The following figure shows the order in which the storage usage fees of NAS file systems are offset.
Example
You purchased a General-purpose NAS resource plan of 500 GiB and an SCU of 100 GiB in the China (Beijing) region in January 2021. In February 2021 in the China (Beijing) region, the storage usage of a Capacity NAS file system is 600 GiB per hour. The following table describes how the resource plan and the SCU offset the monthly usage fees of the file systems.
File system type | Offset by the resource plan | Offset by the SCU |
Capacity NAS file system | You can use 500 GiB of capacity in your resource plan to offset the storage usage fee of 500 GiB for the Capacity NAS file system. | You can use 25 GiB of capacity in your SCU to offset the storage usage fee of the remaining 100 GiB for the Capacity NAS file system. 25 GiB indicates the capacity in the SCU used to offset the storage usage fee of the remaining 100 GiB for the Capacity NAS file system, in addition to the 500 GiB of capacity in the resource plan used to offset the storage usage fee of 500 GiB for the Capacity NAS file system. Calculation formula: (600 GiB - 500 GiB) × 0.25 = 25 GiB |