What Is Performance Pre-Configuration

Usage scenarios for performance preconfiguration

The Cloud Disk Server (CDS) provides distributed block storage services. Typically, performance metrics such as IOPS and throughput improve with increased disk capacity, with larger disks delivering better performance up to their limits. As demands from applications such as AI computing, big data training, and distributed databases grow, higher disk performance is crucial. In such cases, larger disk capacity is often required to meet business performance needs.

CDS now offers the performance preconfiguration capability to meet these requirements. You can obtain disk performance by traditional capacity purchases, or you can configure additional disk performance separately after purchasing a certain disk capacity, so as to achieve the goal of "small capacity disk" with high performance. Currently, this function is available through an allow list. If you need to use it, please submit a ticket to contact us.

Related concepts

CDS disk performance is defined by four key concepts: baseline performance, additional performance, disk performance, and final performance.

• Baseline performance: Refer to the performance included when purchasing capacity. You can calculate the baseline performance corresponding to the capacity based on the Performance Calculation Formula. If you purchase a 100 GB enhanced SSD_PL2, the baseline performance corresponding to 100 GB capacity based on the performance calculation formula would be:

  • IOPS: min{1800+50 x capacity, 100000}=min{1800+50 x 100, 100000}=6800
  • Throughput: min{120+0.5 x capacity, 750}=min{120+0.5 x 100, 750}=170 MBps
• Additional performance: Refer to the additional performance configured for the disk. You can configure additional IOPS when purchasing disks or after completing the purchase. While configuring additional IOPS, CDS will calculate the additional throughput based on the size of a 16 KB file. If you configure an additional 10000 IOPS for the disk, the additional throughput will be 10000x16/1024=156 MBps.

• Disk performance: It can be calculated based on baseline performance and additional performance. Disk performance is not simply the sum of baseline performance and additional performance, and the upper limit of disk performance should also be considered. Taking an enhanced SSD_PL2 disk as an example, its baseline performance, additional performance, and disk performance are as follows:

  • Baseline performance:

    • Baseline IO = min{1800+50*capacity, 100000}
    • Baseline throughput = min{120+0.5 ∗ capacity, 750} MBps

  • Additional performance:

    • Additional IO = min{additional IO, 100000}, where additional IO is a positive integer between 1 and 100,000
    • Additional throughput = min{additional IO * 16 / 1024, 1000} MBps. Additional throughput is a non-negative integer. If the calculation results in a decimal, round down to the nearest integer.

  • Disk performance:

    • Total disk IO = min{baseline IO + additional IO, 100000}
    • Total disk throughput = min{baseline throughput + preconfigured throughput, 1000} MBps
• Final performance: It is the performance that cloud disk can ultimately achieve, which depends on Disk Performance and Speed Limit of Baidu Cloud Compute. When the calculated disk performance is higher than the speed limit of Baidu Cloud Compute, the disk performance will be the final performance. However, when the speed limit of Baidu Cloud Compute is lower than the disk performance, the speed limit of Baidu Cloud Compute shall prevail. For the speed limit of Baidu Cloud Compute (BCC), refer to Baidu Cloud Compute (BCC) Specification Parameters.

Usage method

• Disk type restriction: Currently, additional performance configurations are only supported for enhanced SSD_PL2 type disks.
• Timing: You can configure additional performance when creating a new disk, or adjust the performance of the created disk after creation.
• Charge type: Additional performance is a commercial service, and fees will be charged based on the additional IO size. The charge types include prepay and postpay, and the charge type and lifecycle of additional performance are consistent with the disk capacity.
• Change of disk type restriction: If you initiate a disk type change after completing additional performance configurations, the configured additional performance will become invalid. If your disk is prepaid, the additional performance fees for the remaining time will be refunded to you.
• Disk renewal: If disk renewal is initiated after additional performance configurations are completed, both capacity and additional performance need to be renewed. Renewing capacity or additional performance separately is not supported.
• Change of charge type: If change of charge type for the disk is initiated after additional performance configurations are completed, the charge type for both capacity and additional performance will be changed simultaneously.
• Release of additional performance: Releasing additional performance separately is not supported. Please plan your disk performance before purchasing.
• Service suspension: If your prepaid disk expires without renewal, or if the service of postpaid disk is suspended due to account debts, the service of both capacity and additional performance will be suspended simultaneously, and the system will send you a service suspension notification.