Variable Timeout Control for Disk Access Error Recovery
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Solution Overview
Problem
Conventional information storage devices require a large amount of time to recover from access errors due to identical timeout periods for initial access and retries, leading to reduced response speed in information processing systems.
Innovation Solution
An information storage device with a control unit that sets a shorter first timeout value for initial access and a longer second timeout value for retries, allowing for error source specification and recovery processing, thereby reducing recovery time from access errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an identical timeout value is used for both initial access and access retry, then the error source can be specified before timeout, but the recovery time becomes excessively long
Solution Approach 1:
The patent applies dynamics by making the timeout value variable rather than fixed. The control unit dynamically selects between a first timeout value for initial access and a second timeout value for retry access based on the access state. This dynamic adjustment allows the system to use a shorter timeout during retry operations, reducing recovery time while maintaining error source specification capability through the shorter timeout period.
Solution Approach 2:
The patent changes the parameter of timeout value based on the access state. When the access state indicates a retry operation, the control unit changes the timeout parameter from the first timeout value to the second timeout value, which is set to a shorter period. This parameter change enables faster timeout detection during retries, thereby reducing overall recovery time while still allowing error source specification.
2Loss of time
If a shorter timeout value is used for access retry, then the recovery time is reduced, but the error source specification capability may be compromised
Solution Approach 1:
The patent applies local quality by setting different timeout values for different access states rather than using a uniform timeout. The second timeout value is specifically optimized for retry operations with a shorter duration to reduce recovery time, while the first timeout value for initial access is set longer to ensure adequate error source specification. This localized optimization allows each access state to have the appropriate timeout characteristic for its specific needs.
3Measurement precision
If the timeout period is extended to ensure error source specification, then measurement accuracy is maintained, but the response speed of the information processing system is reduced
Solution Approach 1:
The control unit dynamically adjusts the timeout value based on whether the access is an initial access or a retry access. For retry operations, it uses a shorter second timeout value that enables faster response speed, while for initial access, it uses a longer first timeout value that ensures accurate error source specification. This dynamic adaptation resolves the contradiction by matching the timeout duration to the specific access context.
Solution Approach 2:
The patent changes the timeout parameter based on the access state to optimize both response speed and error source specification accuracy. By switching between the first timeout value (longer, for initial access) and the second timeout value (shorter, for retry access), the system achieves fast response during retries while maintaining specification accuracy during initial access attempts.
Data Source
AI summary
During initial access in which a control unit 8 accesses a disk device 3 for a first time following execution of a command, the control unit 8 waits for an access response from the disk device 3 until a first timeout value, which is set at a time for completing access to the disk device 3, is counted, and during an access retry subsequent to the initial access, the control unit 8 waits for an access response from the disk device 3 until a second timeout value, which is larger than the first timeout value and set at a time required to specify a source of an access error, is counted.