This topic describes the billable items, billing cycle, and billing methods of General-purpose NAS file systems. This topic also compares the billing methods and provides several billing examples.

Billable items

Billable item Description
Storage capacity The maximum used storage space of the file system. Fees are calculated based on the maximum used storage space per hour.
  • The used storage space indicates the total size of all files in a file system. The size of directories is not included. 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. You are charged for the file holes in your NAS file system. A file hole consists of zeros that are not written to a file. You can create a file hole by using the truncate, lseek, or fallocate command.
  • After you enable the recycle bin feature, you are charged for the storage usage of the temporary files in the recycle bin based on the pricing of the original storage type during the retention period. For example, if you delete a file from a Capacity NAS file system, you are charged for the file based on the unit price of storage space in Capacity NAS file systems. Likewise, if you delete a file from an IA storage medium, you are charged for the file based on the unit price of storage space in the IA storage medium. For more information, see Enable the recycle bin feature.

Billing cycle

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

Note The bill that you receive at 09:30:00 may include only the fees that are generated from 07:00:00 to 08:00:00 because of system latency.

Comparison of billing methods

By default, NAS file systems are billed based on the pay-as-you-go billing method. You can also purchase resource plans and storage capacity units (SCUs) to offset fees. The following table compares the operations and billable items that are supported by each billing method. A check sign (✓) indicates that the operation is supported by the billing method. A cross sign (×) indicates that the operation is not supported by the billing method. A hyphen (-) indicates that the operation is not applicable to the billing method.
Note If you have resource plans, SCUs, and storage plans within your Alibaba Cloud account, storage usage fees are offset based on the following sequence: storage plans, resource plans, and SCUs. Then, you are charged based on the pay-as-you-go billing method.
Type Billable item Purchase Offset the storage usage fees of General-purpose NAS file systems of different storage types Offset the storage usage fees of multiple NAS file systems Offset only the storage usage fees of NAS file systems Renewal Upgrade Purchase multiple resource plans
Pay-as-you-go All billable items of NAS file systems - - - - - - -
Resource plan
  • Storage usage of General-purpose NAS file systems
  • Storage usage of IA storage media
Storage plan
  • Storage usage of General-purpose NAS file systems
  • Storage usage of IA storage media
× × × ×
Storage capacity units (SCUs) Storage usage of General-purpose NAS file systems × × ×

Billing method

  • Pay-as-you-go

    After you create a NAS file system, you are billed based on the pay-as-you-go billing method by default.

    The storage usage fee is calculated by using the following formula: Storage usage fee = Maximum usage of a NAS file system per hour × Unit price per hour
    Note
    • You can log on to the NAS console to view the storage usage in the Basic Information section. The storage usage is updated once per hour. In some cases, the storage usage that is displayed in the console at the current local time is the storage usage in the previous hour because of latency.
    • General-purpose NAS file systems are divided into two types: Capacity NAS file system and Performance NAS file system. The two types have different unit prices for storage usage. For NAS file systems, the unit of storage usage fee is USD/GiB/month.When you calculate the storage usage fee, you must convert the unit of measurement to USD/GiB/hour. For more information, see Apsara File Storage NAS pricing.
  • Resource plans (recommended)

    A resource plan is a type of subscription billing method. You can purchase multiple resource plans and use the resource plans to offset the storage usage fees of multiple file systems. Resource plans are applied to offset the fees based on the following sequence: Performance NAS file systems, Capacity NAS file systems, and IA storage media.

    • Purchase method

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

    • Offset rules
      The following table describes the rules that are applied when you use resource plans to offset the storage usage fees of different storage types of NAS file systems in the Chinese mainland. To view the relevant information about the offset rules that are applied in other regions, you can use the calculator.
      Specification Conversion coefficient Description
      Capacity NAS file system 1 You can use 1 GiB of base capacity in your General-purpose NAS resource plan to offset the fee for 1 GiB of storage usage from a Capacity NAS file system.
      Performance NAS file system 5.47 You can use 5.47 GiB of base capacity in your General-purpose NAS resource plan to offset the fee for 1 GiB of storage usage from a Performance NAS file system.
      IA storage media 0.37 You can use 0.37 GiB of base capacity in your General-purpose resource plan to offset the fee for 1 GiB of storage usage from an IA storage medium.
      You can use the calculator that is provided by Alibaba Cloud to calculate the fees that are offset by the resource plans within your account in the current region. This way, you can select appropriate resource plans based on the current storage usage to reduce your costs.
    • Renewal and upgrade

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

  • Storage capacity units (SCUs)

    An SCU is a type of subscription billing method. You can purchase multiple SCUs and use them to offset the storage usage fees of multiple Alibaba Cloud storage services. SCUs are more flexible and cost-effective than storage plans that are dedicated to specific storage services.

    • Purchase method

      For more information about how to purchase SCUs, see Create an SCU.

    • Offset rules
      You can use SCUs to offset the storage usage fees of NAS, Object Storage Service (OSS), and Elastic Compute Service (ECS) resources. The following table describes the rules that are applied when you use SCUs to offset the storage usage fees of different storage classes of NAS file system in the Chinese mainland. For more information about the rules that are applied in other Alibaba Cloud storage services and regions, visit the Pricing page.
      File system type Offset factor Description
      Capacity NAS file system 0.25 You can use 0.25 GiB of capacity in your SCU to offset the fee for 1 GiB of storage usage from a Capacity NAS file system.
      Performance NAS file system 0.889 You can use 0.889 GiB of capacity in your SCU to offset the fee for 1 GiB of storage usage from a Performance NAS file system.
    • Examples
      Mr. Chen purchased a General-purpose NAS resource plan of 500 GiB and an SCU of 40 GiB in the China (Beijing) region in January 2021. In February 2021 in the China (Beijing) region, the storage usage of the Capacity NAS file system is 600 GiB and the storage usage of the Performance NAS file system is 200 GiB. The following table shows the values that are obtained after NAS calculates the monthly usage fee of the file systems based on the resource plan and the SCU.
      File system type Offset by resource plans Offset by SCUs
      Capacity NAS file system You can use 500 GiB of capacity in your resource plan to offset the fee for 500 GiB of storage usage from the Capacity NAS file system. You can use 25 GiB of capacity in your SCU to offset the fee for 100 GiB of storage usage from the Capacity NAS file system.
      Performance NAS file system None You can use 15 GiB of capacity in your SCU to offset 16.87 GiB of storage usage from the Performance NAS file system.
  • Storage plans

    A storage plan is a type of subscription billing method. You can use a storage plan to offset only the storage usage fees of a file system to which the storage plan is attached.

    Notice Alibaba Cloud supports resource plans for Apsara File Storage NAS. You can no longer purchase storage plans. However, you can renew or upgrade existing storage plans. Compared with a storage plan, a resource plan does not need to be bound to a file system. You can purchase multiple resource plans to offset the storage usage fees of multiple file systems.
    • Offset rules
      • After you purchase a storage plan, NAS offsets fees from the storage plan based on the storage usage of your file system.
      • You can attach only one storage plan to a General-purpose NAS file system. When you delete the General-purpose NAS file system, the storage plan is automatically detached. You can attach the detached storage plan to another file system of the same type in the same region to offset storage usage fees.
    • Renewal and upgrade

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

Billing examples

Example 1: Mr. Zhang has created a Performance NAS file system named File System A in the China (Beijing) region. The storage usage of File System A in January 2021 is 100 GiB per hour. In the storage usage, 10 GiB of data is stored in a General-purpose NAS file system, and 90 GiB of data is stored in an IA storage medium. The read traffic of the IA storage medium is 1 GiB and the write traffic of the IA storage medium is 2 GiB within the month. The following table lists the fees that are incurred by File System A within the month based on storage plans and the pay-as-you-go billing method.
Billing method Billing
Pay-as-you-go
  • Storage usage fee of General-purpose NAS file system = 10 GiB × USD 0.3/GiB/month = USD 3
  • Storage usage fee of the IA storage medium = 90 GiB × USD 0.02322/GiB/month = USD 2.0898
  • Read and write traffic fees of the IA storage medium
    • Read traffic fee = 1 GiB × USD 0.00929/GiB = USD 0.00929
    • Write traffic fee = 2 GiB × USD 0.00929/GiB = USD 0.01858
Total fee = USD 3 + USD 2.0898 + USD 0.00929 + USD 0.01858 = USD 5.11767
Resource plan for General-purpose NAS file systems (100 GiB, one month) The 100 GiB of storage capacity in the resource plan is used to first offset 10 GiB of storage usage from the Performance NAS file system. The remaining storage capacity of the resource plan is calculated by using the following equation: 100 GiB - 10 GiB × 5.47 = 45.3 GiB.

The 45.3 GB of storage capacity is then used to offset 90 GiB of storage usage from the IA storage medium. The remaining storage capacity of the resource plan is calculated by using the following equation: 45.3 GiB - 90 GiB × 0.37 =12 GiB.

Only the pay-as-you-go billing method can be used to calculate the read and write traffic fees of IA storage media.
  • Read traffic fee = 1 GiB × USD 0.00929/GiB = USD 0.00929
  • Write traffic fee = 2 GiB × USD 0.00929/GiB = USD 0.01858

Total fee = USD 4.57 + USD 0.00929 + USD 0.01858 = USD 4.59787

USD 4.57 is the fee of a resource plan (100 GiB, one month) for a General-purpose NAS file system in the China (Beijing) region.

Example 2: Mr. Zhang has created a Performance NAS file system named File System A in the China (Beijing) region. The storage usage of File System A in January 2021 is 210 GiB per hour. In the storage usage, 10 GiB of data is stored in a General-purpose NAS file system and 200 GiB of data is stored in an IA storage medium. The read traffic of the IA storage medium is 1 GiB, and the write traffic of the IA storage medium is 2 GiB within the month. Mr. Zhang also has a Capacity NAS file system named File System B. The storage usage of File System B in January 2021 is 90 GiB per hour. The following table lists the fees that are incurred by File System A and File System B within the month based on storage plans and the pay-as-you-go billing method.
Billing method Billing
Pay-as-you-go
  • Storage usage fees of the General-purpose NAS file system
    • Storage usage fee of the Performance NAS file system = 10 GiB × USD 0.3/GiB/month = USD 3
    • Storage usage fee of the Capacity NAS file system = 90 GiB × USD 0.06/GiB/month = USD 5.4.
  • Storage usage fee of the IA storage medium = 200 GiB × USD 0.02322/GiB/month = USD 4.644
  • Read and write traffic fees
    • Read traffic fee = 1 GiB × USD 0.00929/GiB = USD 0.00929
    • Write traffic fee = 2 GiB × USD 0.00929/GiB = USD 0.01858
Total fee = USD 3 + USD 5.4 + USD 4.644 + USD 0.00929 + USD 0.01858 = USD 13.07187
Two resource plans for General-purpose NAS file systems (100 GiB, one month) The 100 GiB of storage capacity in the resource plans is used to first offset 10 GiB of storage usage from the Performance NAS file system. The remaining storage capacity of the resource plan is calculated by using the following equation: 200 GiB - 10 GiB × 5.47 = 145.3 GiB. The 145.3 GiB of storage capacity is then used to offset 90 GiB of storage usage from the IA storage medium. The remaining storage capacity of the resource plan is calculated by using the following equation: 145.3 GiB - 90 GiB × 1 = 55.3 GiB.

The 55.3 GiB of storage capacity is then used to offset 149.5 GiB of storage usage from the IA storage medium (55.3 GiB/0.37 ≈ 149.5 GiB). The excess storage usage of the IA storage medium is 50.5 GiB (200 GiB - 149.5 GiB = 50.5 GiB) is calculated based on the pay-as-you-go billing method by using the following equation: 50.5 GiB × USD 0.02322 = USD 1.17261.

Only the pay-as-you-go billing method can be used to calculate the read and write traffic fees of IA storage media.
  • Read traffic fee = 1 GiB × USD 0.00929/GiB = USD 0.00929
  • Write traffic fee = 2 GiB × USD 0.00929/GiB = USD 0.01858

Total fee = USD 4.57 × 2 + USD 1.17261 + USD 0.00929 + USD 0.01858 = USD 10.34048

USD 4.57 is the fee of a resource plan (100 GiB, one month) for a General-purpose NAS file system in the China (Beijing) region.

Example 3: Mr. Zhang has created a Capacity NAS file system named File System A in the China (Beijing) region. The storage usage of File System A in January 2021 is 1000 GiB per hour. In the storage usage, 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 read traffic in the IA storage medium is 1 GiB and the write traffic in the IA storage medium is 2 GiB within the month. The following table lists the fees that are incurred by File System A within the month based on storage plans and the pay-as-you-go billing method.
Billing method Billing
Pay-as-you-go
  • Storage usage fee of the General-purpose NAS file system: 200 GiB × USD 0.06/GiB/month = USD 12
  • Storage usage fee of the IA storage medium = 800 GiB × USD 0.02322/GiB/month = USD 18.576
  • Read and write traffic fees
    • Read traffic fee = 1 GiB × USD 0.00929/GiB = USD 0.00929
    • Write traffic fee = 2 GiB × USD 0.00929/GiB = USD 0.01858
Total fee = USD 12 + USD 18.576 + USD 0.00929 + USD 0.01858 = USD 30.60387
Storage plan (500 GiB, one month) The 500 GiB of storage capacity in the resource plan is used to first offset 200 GiB of storage usage from the Capacity NAS file system. The remaining capacity of the resource plan is calculated by using the following equation: 500 GiB - 200 GiB = 300 GiB.

The 300 GiB of storage capacity is then used to offset 699.9 GiB of storage usage from the IA storage medium (300 GiB × 2.333 = 699.9 GiB). The excess storage usage of the IA storage medium is 100.1 GiB (800 GiB - 699.9 GiB = 100.1 GiB). The fee for this storage usage is calculated based on the pay-as-you-go billing method by using the following equation: 100.1 GiB × USD 0.02322 = USD 2.324322.

Only the pay-as-you-go billing method can be used to calculate the read and write traffic fees of IA storage media.
  • Read traffic fee = 1 GiB × USD 0.00929/GiB = USD 0.00929
  • Write traffic fee = 2 GiB × USD 0.00929/GiB = USD 0.01858

Storage usage fee = USD 22.85 + USD 2.324322 + USD 0.00929 + USD 0.01858 = USD 25.202192

USD 22.85 is the fee of a storage plan (500 GiB, one month) for a Capacity NAS file system in the China (Beijing) region.

Example 4: Mr. Wang has created a Capacity NAS file system in the China (Hangzhou) region. The maximum storage usage per hour in January 2021 is 90 GiB. The following table shows the monthly fees that were generated by the file system based on resource plans and the pay-as-you-go billing method.
Billing method Billing
Pay-as-you-go Storage usage fee = 90 GiB × 0.06 USD/GiB/month = USD 5.4.
General-purpose NAS resource plan (100 GiB, one month) Storage usage fee = USD 4.57

The fee for a General-purpose NAS resource plan (100 GiB, one month) in the China (Beijing) region is USD 4.57.

Example 5: Mr. Zhang has created a Performance NAS file system and a Capacity NAS file system in the China (Hangzhou) region. The maximum storage usage per hour for the Performance NAS file system in January 2021 is 20 GiB. The maximum storage usage per hour for the Capacity NAS file system in January 2021 is 90 GiB. The following table shows the monthly fees that were generated by the file systems based on resource plans and the pay-as-you-go billing method.
Billing method Billing
Pay-as-you-go Total fee = 90 GiB × USD 0.06/GiB/month + 20 GiB × USD 0.3/GiB/month = USD 11.4
General-purpose NAS resource plan (100 GiB, one month) The 100 GiB of storage capacity in the resource plan is used to offset the fee for 18.28 GiB (100 GiB/5.47≈18.28 GiB) of storage usage from the Performance NAS file system. The fees for the excess storage usage are calculated based on the pay-as-you-go billing method.

Total fee = USD 4.57 + (20 - 18.28) GiB × USD 0.3/GiB/month + 90 GiB × USD 0.06/GiB/month = USD 10.486

The fee for a General-purpose NAS resource plan (100 GiB, one month) in the China (Beijing) region is USD 4.57.

General-purpose NAS resource plan (200 GiB, one month) Total fee = USD 9.14

The fee for a General-purpose NAS resource plan (200 GiB, one month) in the China (Hangzhou) region is USD 9.14.

FAQ