If you enable lifecycle management for your General-purpose NAS file system, data that meets the specified lifecycle management policies is dumped to an Infrequent Access (IA) storage medium. You are charged for the used space of the IA storage medium and read/write traffic. This way, you can use this feature to reduce the costs of your file system. This topic describes the billing method of General-purpose NAS file systems for which the lifecycle management feature is enabled.

Billable items

Note IA storage media cannot be separately purchased. For more information, see IA storage medium.
Billable item Description
Storage usage The usage of a General-purpose NAS file system and the usage of an IA storage medium. Fees are calculated based on the maximum used storage per hour.
  • The used storage space indicates the total size of all files in a file system. The size of directories is not counted. The basic storage unit is 4 KiB. If the size of a file is less than 4 KiB, the billed storage space of the file is rounded up to 4 KiB. If the size of a file is larger than 4 KiB, the billed storage space is rounded up to the nearest multiple of 4 KiB. For example, if the size of a file is 2 KiB, the size of the file is counted as 4 KiB. If the size of a file is 6KiB, the size of the file is counted as 8 KiB.
  • File holes occupy storage space in NAS. Therefore, you are billed for the file holes in your NAS file system. A file hole consists of zeros that are not written to a file. A file hole can be created by using the truncate, lseek, or fallocate command.
Read/write traffic Traffic fees are incurred when the data in an IA storage medium is accessed. Fees are calculated based on the total amount of read/write traffic per hour. The amount of read/write traffic is reset to 0 each time an hourly bill is generated. The amount of read/write traffic starts from 0 again for subsequent hours.
  • If the data in the file system meets the lifecycle management rules, the data is automatically dumped to the IA storage medium. No write traffic fees are incurred for the data transfer.
  • If you access files in an IA storage medium, you are charged for the actual read and write traffic.
  • If you run a data retrieval task, you are charged for read traffic based on the size of the retrieved files.
  • If you back up files from an IA storage medium, you are charged for read traffic based on the size of the files.

Billing cycle

The fees incurred within an hour are deducted from your account balance in the next hour. For example, you are billed at 09:30 for the fees incurred from 08:00 to 09:00.

Note If you receive a bill at 09:30, the bill may include fees only from 07:00 to 08:00 due to system latency.

Billing methods

If your Alibaba Cloud account have both storage plans and storage capacity units (SCUs), resource fees are first deducted by storage plans. If your storage plans have insufficient balance, resource fees are deducted by SCUs. If your storage plans and SCUs are both exhausted, the billing method is changed to pay-as-you-go.

  • Pay-as-you-go
    Formula: Space usage fee = Usage fee of a General-purpose NAS file system + Usage fee of an IA storage medium + Traffic fee of the IA storage medium = Maximum usage of a General-purpose NAS file system per hour × Unit price per hour + Maximum usage of an IA storage medium per hour × Unit price per hour + Amount of read traffic × Unit price per hour + Amount of write traffic × Unit price per hour
    Note
    • If the lifecycle management feature is enabled, the usage of the General-purpose NAS file system is a storage space. This storage space is occupied by the data that is not dumped to an IA storage medium.
    • Only the pay-as-you-go billing method is applied to the read/write traffic of IA storage media.
  • Storage plans

    You can purchase a storage plan to deduct the resource usage fees of a General-purpose NAS file system. You can reserve resources and reduce costs by using storage plans.

    • Purchase method

      For more information about how to purchase a storage plan, see Manage storage plans.

    • Usage rules
      • A storage plan is used to first deduct the fees for the used storage space. If the storage plan still has a positive balance, the storage plan is used to deduct the fees for the used space of an IA storage medium. The fees are deducted based on a specific coefficient.
        • If the following condition is met, the storage plan is sufficient to deduct all of the fees for the usage of the IA storage medium. The following example describes the formula that is used to calculate the equation: (Capacity of the storage plan - Usage of the General-purpose NAS file system) × Coefficient - Usage of the IA storage medium ≥ 0 GiB.
        • If the following condition is met, the storage plan is insufficient to deduct all of the fees for the usage of the IA storage medium. The following example describes the formula that is used to calculate the equation: (Capacity of the storage plan - Usage of the General-purpose NAS file system) × Coefficient - Usage of the IA storage medium < 0 GiB. The fees for the remaining used storage space are calculated based on the pay-as-you-go billing method.

          The coefficient in the preceding formulas varies based on the type of a file system. For Performance NAS file systems, the coefficient is 12.333. For Capacity NAS file systems, the coefficient is 2.333.

      • You can attach only one storage plan to a General-purpose NAS file system at a time. If you delete a General-purpose NAS file system, its storage plan is automatically detached. However, the detached storage plan can be attached to another file system of the same type in the same region. This can be used to deduct the fees for storage usage.
    • Renewal and upgrade

      You can renew and upgrade a storage plan. For more information, see Manage storage plans.

Examples

Mr. Zhang has created a Capacity NAS file system named File System A in the China (Beijing) region. The used storage space of File System A from 10:00 to 11:00 on January 1, 2021 is 1,000 GiB. In the used storage space, 200 GiB of data is stored in a General-purpose NAS file system, and 800 GiB of data is stored in an IA storage medium. The amount of read traffic in the IA storage medium is 1 GiB within the hour. The amount of write traffic in the IA storage medium is 2 GiB. The following tables list the fees that are incurred by File System A within the hour based on storage plans and the pay-as-you-go billing method.
Table 1. Pay-as-you-go
Billable item Billing
Usage of a General-purpose NAS file system Space usage fee = 200 GiB × 0.06 USD/GiB/month/30 days/24 hours = USD 0.0166666667
Usage of the IA storage medium Space usage fee = 800 GiB × 0.0000322450 USD/GiB/month/30 days/24 hours = USD 0.0000358277
Read traffic of the IA storage medium Read traffic fee = 1 GiB × 0.0092866 USD/GiB = USD 0.0092866
Write traffic of the IA storage medium Write traffic fee = 2 GiB × 0.0092866 USD/GiB = USD 0.0185732
Hourly space usage fee = USD 0.0166666667 + USD 0.000035827 + USD 0.0092866 + USD 0.0185732 = USD 0.0445622944
If Mr. Zhang used the same amount of storage space within each hour of the month, the monthly fee is calculated by using the following formula: Monthly fee = USD 0.0445622944 × 24 hours × 30 days = USD 32.084851968
Table 2. Storage plan (500 GiB, one month)
Billable item Billing
Usage of a General-purpose NAS file system Space usage fee = 200 GiB × 23 USD/month/30 days/24 hours/500 GiB = USD 0.0127777778

In the preceding formula, USD 23 is the fee for the storage plan (500 GiB, one month).

Usage of the IA storage medium (500 GiB -200 GiB) × 2.333 - 800 GiB = -100.1 GiB < 0 GiB. Therefore, the storage plan is insufficient to deduct all of the fees for the usage of the IA storage medium.

The fees for the remaining used storage space are calculated based on the pay-as-you-go billing method. Space usage fee = 100.1 GiB × 0.0000322450 USD/GiB/month/30 days/24 hours = USD 0.0000044829

Read traffic of the IA storage medium Read traffic fee = 1 GiB × 0.0092866 USD/GiB = USD 0.0092866
Write traffic of the IA storage medium Write traffic fee = 2 GiB × 0.0092866 USD/GiB = USD 0.0185732
Hourly space usage fee = USD 0.0127777778 + USD 0.0000044829 + USD 0.0092866 + USD 0.0185732 = USD 0.0406420607
If Mr. Zhang used the same amount of storage space in File System A within each hour of the month, the monthly fee is calculated by using the following formula: Monthly fee = USD 0.0406420607 × 24 hours × 30 days = USD 29.262283704

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