Semi-Exclusive Write Lock for Cluster Storage Deadlock Resolution
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Solution Overview
Problem
Cluster file storage systems face deadlocks when multiple nodes attempt to access the same data, leading to inefficiencies and the need for conventional DLM operations that often involve read locks to resolve these issues.
Innovation Solution
Implementing a semi-exclusive write lock mechanism that uses a reserved portion of the storage medium for lock information, allowing nodes to synchronize access and avoid deadlocks by asserting and de-asserting locks based on timestamp and node number validation, thereby eliminating the need for read locks and queues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DLM operations with read locks and queues are used to manage data access, then access control and deadlock resolution are achieved, but system complexity and operational overhead increase
Solution Approach 1:
The patent extracts and eliminates the read lock mechanism from the conventional DLM operation, retaining only the essential write lock functionality. By removing read locks and their associated queue management, the system achieves simpler operations while maintaining deadlock resolution capability through the simplified write lock assertion mechanism.
Solution Approach 2:
Instead of using read locks to prevent deadlocks as in conventional systems, the patent inverts the approach by using a simplified write lock mechanism that automatically resolves deadlocks through timestamp-based priority arbitration. This inversion eliminates the need for complex read lock management while achieving the same reliability goal.
2Reliability
If read locks are used to resolve deadlocks in conventional DLM operations, then access control is improved, but time consumption increases due to queuing and lock management overhead
Solution Approach 1:
The patent removes the time-consuming read lock acquisition and queue waiting processes from the system. By extracting only the essential write lock functionality and eliminating read lock management, the system reduces time loss while maintaining access control through the simplified lock mechanism.
Solution Approach 2:
The patent implements a rushed-through approach by using timestamp-based priority arbitration that immediately resolves access conflicts without requiring prolonged queuing or multiple lock acquisition attempts. The simplified write lock mechanism allows nodes to quickly determine access rights based on timestamps, reducing the time lost in lock management.
3Reliability
If multiple nodes queue for access to the same data, then access control is maintained, but productivity decreases due to sequential processing requirements
Solution Approach 1:
The patent introduces dynamic timestamp-based priority arbitration that allows nodes to access data in parallel based on their timestamps rather than strict sequential queuing. This dynamic resolution mechanism maintains access control while significantly improving productivity by enabling concurrent operations for nodes with appropriate timestamps.
Solution Approach 2:
The patent segments the access control mechanism into independent timestamp validation and lock assertion operations. This segmentation allows multiple nodes to perform validation simultaneously and reduces the sequential processing requirement, thereby improving throughput while maintaining controlled access through the timestamp-based priority system.
Data Source
AI summary
Apparatus, systems, and methods may operate to assert a first semi-exclusive write lock with respect to a storage medium area by storing lock information when assertion of another semi-exclusive write lock with respect to the area is not detected. Additional activities may include writing data to the area by a writing entity that has asserted the first semi-exclusive write lock after determining the lock information has not changed, while substantially simultaneously de-asserting the first semi-exclusive write lock. Reading from the area may be determined as successful by determining that the semi-exclusive write lock was not asserted prior to or during the reading by checking the status of the lock information. Additional apparatus, systems, and methods are disclosed.