Storage capacity units (SCUs) are subscription resource plans that offset the storage fees of multiple Alibaba Cloud storage services. Compared with storage plans dedicated to a single service, SCUs offer greater flexibility and cost-effectiveness.
Scenarios
SCUs suit scenarios that require low storage costs and flexible disk creation. Examples:
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DevOps or microservices workloads that require frequent interactions and adjustments across development, testing, and production environments.
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Container-native or mobile gaming workloads where multiple projects run simultaneously and applications are delivered or released frequently.
You can use SCUs in one of the following patterns:
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Pattern 1: You have multiple pay-as-you-go disks whose historical bills show a roughly stable monthly disk space consumption. You can purchase SCUs to reduce monthly storage costs.
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Pattern 2: Your quarterly or annual storage budget requires a centralized purchase or advance payment. After you estimate the required capacity from historical data and your budget, you can purchase SCUs and then create pay-as-you-go disks as needed.
Billing method
SCUs use the subscription billing method. You are charged based on the capacity and validity period of each SCU. For more information, see SCUs.
Applicable products
The following table lists the services that SCUs can be applied to.
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Applicable products |
Deduction rules |
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EBS |
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OSS |
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NAS |
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Snapshot |
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Cloud Backup |
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PDS |
Offset rules
After you purchase an SCU in a region, it automatically matches eligible pay-as-you-go storage resources in that region and offsets their bills until the SCU expires. When the used capacity exceeds the SCU capacity, the excess is billed on a pay-as-you-go basis. For more information, see Offset rules.
Limits
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You cannot upgrade or renew SCUs.
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SCUs can be used to offset only the fees for pay-as-you-go resources, but not for pay-as-you-go disks attached to preemptible instances.
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You can configure an effective time for each SCU. The effective time can be up to six months from the creation time of the SCU.
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SCU capacity limits are determined by the EBS capacity in your account. For more information about the SCU capacity limits per region, see Limits.
Lifecycle
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If you select 'Take effect immediately' at the time of purchase:
The SCU takes effect on the hour of purchase and expires at 00:00:00 on the day after the expiration date. It offsets pay-as-you-go storage bills from the effective time to the expiration time.
For example, you purchase a 10-TiB SCU with a validity period of 1 year at 09:10:00 on August 20, 2019. The SCU takes effect at 09:00:00 on August 20, 2019 and expires at 24:00:00 on August 21, 2020.
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If you set an effective date at the time of purchase:
The SCU takes effect at the specified time and expires at 00:00:00 on the day after the expiration date. It offsets pay-as-you-go storage bills from the effective time to the expiration time.
For example, you purchase a 10-TiB SCU with a validity period of 1 year at 09:15:00 on August 20, 2019 and set the effective time to 01:00:00 on November 19, 2019. The SCU takes effect at 01:00:00 on November 19, 2019 and expires at 24:00:00 on November 20, 2020.
