Burst performance capability
Overview
Baidu AI Cloud CDS is the first in China to offer burst performance capability, allowing customers to temporarily exceed the cloud disk's performance limit. For instance, a disk purchased with 200 IOPS can burst up to 1,300 IOPS for a limited duration.
As illustrated in the table below, when a business opts for physical block storage, performance requirements dictate the type of block storage, while data volume requirements determine the storage capacity. On the other hand, for cloud-based block storage, performance requirements determine the storage class, and both performance and data volume requirements collectively influence the storage capacity. This is because the performance of cloud-based block storage is directly proportional to its capacity. Therefore, for intermittent high-I/O performance needs, traditional cloud disk services often require purchasing a larger disk capacity than the actual data demand to meet performance requirements. However, the burst capability provided by Baidu AI Cloud Disk Server (CDS) resolves this issue. Now, businesses can simply purchase a disk based on actual data volume requirements, while the burst capability of CDS addresses intermittent high-I/O performance demands.
| Category | Basis for physical block storage selection | Basis for cloud block storage selection |
|---|---|---|
| Block storage class | Performance requirement | Performance requirement |
| Block storage capacity | Data volume requirement | Performance & data volume requirements |
Advantages
CDS allows disks of any size to burst to the maximum performance of their type
During disk operation, any unused performance below the specified nominal level is added to the burst pool. Specifically, the burst pool accumulates as an integral of (nominal performance - actual running IO) over time. When the burst pool contains accumulated resources, the disk can perform bursts. During a burst, the resources in the burst pool are consumed, and once depleted, the disk returns to its nominal performance level. The available burst duration is calculated as: Burst duration = Burst pool accumulation / (Burst IO - Nominal IO performance).
Here is an example to clarify how CDS performance bursting works. Assume the maximum burst pool capacity is 1,600,000 IO, and the throughput is estimated at 128 KB per IO. For a disk with a nominal performance of 1,000 IOPS that operates at 200 IOPS for 1 hour, the accumulated available IO in the burst pool is: min((1,000 - 200) 3,600, 1,600,000), and the corresponding accumulated available data volume in the burst pool is: min((1,000 - 200) 3,600 128 KB, 1,600,000 128 KB).