Controller Segmentation for Storage Mirroring Response Latency
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Solution Overview
Problem
Information processing apparatuses with mirroring functions face challenges in managing varying write/read speeds across multiple storage devices, such as HDDs and SSDs, due to differences in performance and aging degradation, leading to potential errors and system failures when one storage device fails to respond within a predetermined time.
Innovation Solution
The apparatus includes a controller with separate communication interfaces for each storage device, allowing it to continue data transmission to responsive devices while stopping data transmission to non-responsive devices, and issuing completion notifications based on successful writes from active storage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller waits for responses from all storage devices before returning completion to host controller, then data integrity is ensured, but system productivity decreases when some storages are slow or non-responsive
Solution Approach 1:
The controller segments the completion notification process by issuing completion to the host controller as soon as at least one storage device confirms successful writing, rather than waiting for all storages. This segmentation allows the system to proceed with productivity while maintaining reliability through selective confirmation.
Solution Approach 2:
The controller applies partial action by requiring only a subset of storage devices (at least one) to confirm successful writing before issuing completion to the host controller, rather than requiring all storage devices. This partial requirement balances reliability with improved productivity.
2Stability of the object's composition
If the controller continues transmission to all storage devices, then mirroring function is maintained, but harmful factors increase when one storage device is non-responsive
Solution Approach 1:
The controller extracts the non-responsive storage device from the active mirroring operation by stopping data transmission to it while continuing to write to responsive storage devices. This isolation prevents error propagation while maintaining the essential mirroring function through the responsive devices.
Solution Approach 2:
The controller acts as an intermediary that selectively routes data transmission based on response status. It mediates between the host controller and multiple storage devices, directing writes only to responsive storages and preventing harmful error propagation to non-responsive devices.
3Reliability
If the controller issues completion notification only after all storages confirm, then reliability is improved, but loss of time increases due to waiting for slow storages
Solution Approach 1:
The controller performs preliminary action by issuing completion notification to the host controller as soon as at least one storage device confirms successful writing, before all storage devices have responded. This preliminary completion reduces response time while maintaining reliability through subsequent tracking of all storage statuses.
Data Source
AI summary
An information processing apparatus in which a controller continues transmission, based on a status in which a response to a writing instruction is received from a first storage device, and a response to the writing instruction is not received from a second storage device, of data to the first storage device, and stops transmission of data to the second storage device, and based on a status in which a second communication IF receives a completion notification of storing of the data that is issued by the first storage device, a first communication IF transmits a completion notification of processing corresponding to the writing instruction.