Write Blocking for Spontaneous De-staging in Storage Systems
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Solution Overview
Problem
Data storage systems face challenges in managing physical storage devices to prevent them from entering background task mode during spontaneous de-staging events, which can lead to incomplete data transfer due to insufficient cumulative storage capacity and performance degradation.
Innovation Solution
Implementing a user-defined background task threshold (UBTT) that is lower than the vendor-defined threshold (VBTT) to control when physical storage devices enter background task mode, along with write blocking management techniques to ensure adequate storage capacity is reserved for spontaneous de-staging, and providing flexibility to manage physical storage devices based on workload conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical storage devices use vendor-defined background task threshold (VBTT) to determine when to enter background task mode, then the storage devices can perform background maintenance tasks, but the cumulative storage capacity may be insufficient during spontaneous de-staging events causing incomplete data transfer
Solution Approach 1:
The patent changes the threshold parameter from vendor-defined (VBTT) to user-defined (UBTT), allowing dynamic adjustment of when background tasks are triggered. This enables optimization of storage capacity availability during critical operations like spontaneous de-staging while still allowing background maintenance tasks to occur under controlled conditions.
Solution Approach 2:
The system dynamically adjusts the background task threshold based on operational conditions, transitioning from a static vendor-defined threshold to a flexible user-configurable threshold that can be modified in real-time to match system needs and workload conditions.
2Productivity
If physical storage devices enter background task mode during spontaneous de-staging, then background maintenance can be performed, but performance degradation occurs and de-staging may be incomplete
Solution Approach 1:
The system preemptively prevents background tasks from being triggered during spontaneous de-staging operations by adjusting the threshold parameter. This preliminary action avoids the harmful effect of performance degradation and ensures complete data transfer before background maintenance interferes with the critical de-staging process.
Solution Approach 2:
The system performs preliminary configuration of the background task threshold to ensure adequate storage capacity is reserved before spontaneous de-staging events occur, preventing the harmful interaction between background tasks and de-staging operations.
3Quantity of substance
If user-defined background task threshold (UBTT) is set lower than vendor-defined threshold (VBTT), then more storage capacity is reserved for spontaneous de-staging, but background maintenance tasks are triggered more frequently
Solution Approach 1:
The system makes the background task threshold dynamic and user-configurable, allowing optimization of the balance between reserved storage capacity and background task frequency based on specific operational requirements and workload patterns.
Solution Approach 2:
By changing the threshold parameter from fixed (VBTT) to adjustable (UBTT), the system enables fine-tuning of the trade-off between ensuring sufficient storage capacity for de-staging operations and maintaining appropriate background maintenance task frequency.
4Reliability
If write blocking is implemented to control storage capacity availability, then spontaneous de-staging can complete successfully, but I/O write operations are blocked
Solution Approach 1:
The system preemptively blocks writes only when necessary to prevent the harmful effect of insufficient storage capacity during spontaneous de-staging. This targeted approach maintains I/O accessibility under normal conditions while ensuring de-staging completion when critical.
Data Source
AI summary
Writes to one or more physical storage devices may be blocked after a certain storage consumption threshold (WBT) for each physical storage device. A WBT for certain designated physical storage devices may be applied in addition to, or as an alternative to, determining and applying a user-defined background task mode threshold (UBTT) for certain designated physical storage devices. In some embodiments, the WBT and UBTT for a physical storage device designated for spontaneous de-staging may be a same threshold value. Write blocking management may include, for each designated physical storage device, blocking any writes to the designated physical storage device after a WBT for the designated physical storage device has been reached, and restoring (e.g., unblocking) writes to the designated physical storage device after storage consumption on the physical storage device has been reduced to a storage consumption threshold (WRT) lower than the WBT.