Expander Restart Control for Data Storage Systems
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Solution Overview
Problem
Current data storage systems face challenges in efficiently restarting the expander after a watchdog timeout, leading to prolonged waiting times for disk groups to become ready, which can result in data damage if the error-handling mechanism exceeds one minute.
Innovation Solution
A control method that utilizes a temporary memory device to store a ready flag, allowing the expander to detect readiness and send a simultaneous link-reset instruction to all disk groups, reducing the time required for all disk groups to become operational.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expander supplies power to disk groups sequentially and individually after restart, then power tripping is avoided, but the time for all disk groups to become ready exceeds one minute
Solution Approach 1:
The patent applies preliminary action by setting the ready flag in the temporary memory device before the expander restart. This allows the expander to immediately detect that all disk groups are ready upon restart, eliminating the need for sequential power supply waiting and enabling simultaneous activation of all disk groups within the one-minute error-handling time limit.
2Reliability
If the RAID control device waits for all disk groups to be ready, then data integrity is maintained, but the error-handling time limit of one minute is exceeded
Solution Approach 1:
The patent introduces an intermediary mechanism - the ready flag stored in the temporary memory device - that communicates the readiness status of disk groups to the expander. This intermediary allows the expander to quickly determine readiness without waiting for sequential power supply completion, maintaining data integrity while staying within the one-minute error-handling time limit.
3Loss of time
If the expander sends link-reset instruction to all disk groups simultaneously, then restart time is reduced, but power tripping may occur
Solution Approach 1:
The patent applies preliminary action by pre-setting the ready flag in temporary memory before restart. This allows the expander to safely send simultaneous link-reset instructions to all disk groups knowing they are ready, reducing restart time while avoiding power tripping that would occur with simultaneous activation of uninitialized disk groups.
Data Source
AI summary
The present disclosure discloses a data storage system and a control method thereof. The data storage system includes a plurality of data storage devices, a temporary memory device and an expander. The control method includes: detecting, by the expander, if a flag is in a first status after the expander is restarted; sending, by the expander, a first command to all the data storage devices if the first status is detected. The first status indicates that all the data storage devices are ready for linking and operation.