I/O Performance Quotas for Storage Systems
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Solution Overview
Problem
Existing storage systems face challenges in efficiently and reliably providing a guaranteed level of service to multiple independent users or groups, especially when configuration and load levels change frequently, as they struggle to allocate resources effectively to maintain response time and data transfer efficiency.
Innovation Solution
Implementing a quota system for I/O operations that sets a maximum amount of data to store within a given time, allowing I/O operations if the quota is not exceeded, accumulating credit for underutilized periods, and performing operations when credit is available, while maintaining a queue for pending operations and providing alerts for quota attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple independent users share a storage device without formal resource allocation, then storage capacity is maximized, but service level guarantees and response time cannot be ensured
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting I/O operation rates and credit values based on quota violations and system conditions. The quota mechanism changes operational parameters (I/O rates, credit accumulation) to enforce service level agreements while managing shared storage resources effectively.
Solution Approach 2:
The patent implements feedback through the credit system that tracks quota compliance and adjusts future I/O permissions accordingly. When users exceed their quotas, the system provides feedback by denying additional I/O operations until credit is replenished, creating a self-regulating mechanism for resource allocation.
2Reliability
If I/O operations are strictly limited by quota to guarantee service levels, then response time is improved, but productivity and data transfer efficiency decrease
Solution Approach 1:
The patent applies preliminary action by pre-allocating credit to users based on their quotas before I/O operations occur. This allows users to accumulate credit during periods of low utilization, preparing them in advance for future I/O bursts without immediately limiting their productivity when needs arise.
Solution Approach 2:
The patent implements dynamics through the time-varying credit system that allows I/O rates to fluctuate based on current quota status and accumulated credit. The system dynamically adjusts operational flexibility, permitting higher throughput when credit is available while maintaining response time guarantees when quotas are violated.
3Productivity
If credit accumulation is allowed for underutilized periods, then productivity during peak times is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service through the automated credit accumulation and tracking system that operates without continuous manual intervention. The system automatically credits users for underutilized periods, manages quota violations, and adjusts I/O permissions based on credit balance, reducing operational complexity despite the sophisticated credit management mechanism.
Data Source
AI summary
Controlling I/O operations with a storage device includes establishing a quota that corresponds to a maximum amount of data to store on the storage device in a given amount of time, determining if processing an I/O operation would cause the quota to be exceeded, and performing the I/O operation if the quota is not exceeded. The quota may be provided in I/O operations per second or as I/O throughput. Controlling I/O operations with a storage device may also include accumulating credit in response to a rate of I/O operations being less than the quota and performing I/O operations when the quota is exceeded in response to the credit being greater than zero. The credit may be decreased if an I/O operation is performed when the quota is exceeded.