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Following is the share about SmartQos solution.
I/O Traffic Control - Overview
I/O traffic control restricts the performance of non-critical applications by limiting their IOPS or bandwidth, thereby preventing them from affecting critical applications. I/O traffic control is implemented based on hierarchical management, objective distribution, and traffic control management.
Key technology - Burst Traffic Management
The burst capability of a LUN comes from the burst credits converted from performance accumulated when the actual performance of the LUN is lower than the upper limit.
SmartQoS uses the dual-token-bucket mode to support the production and consumption of burst credits. As shown in the right figure, Token bucket C is used to implement upper limit control, and Token bucket E is used to implement burst control.
If the LUN's service pressure is lower than the configured performance upper limit, that is, the consumption rate is lower than the production rate of tokens in Token bucket C, the number of tokens in Token bucket C gradually increases and overflows when it exceeds the bucket depth. Excessive tokens are stored in Token bucket E until the number of tokens in it also exceeds the bucket depth. At this time, excessive tokens are discarded. Only when Token bucket E has remaining tokens, the LUN has the burst capability.
If the LUN's service pressure is greater than the configured performance upper limit, tokens in Token bucket C will be exhausted gradually. When Token bucket C has no token, it attempts to borrow tokens from Token bucket E until tokens in Token bucket E is exhausted.
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