Storage Device Metadata Recovery via Power Hold-Up and Binary Search
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Solution Overview
Problem
Computer storage devices face data loss due to sudden power loss, as volatile memory loses data quickly when power is interrupted, and existing solutions do not efficiently recover the meta data necessary for resuming operations.
Innovation Solution
A computer storage device configuration that maintains meta data in volatile memory and copies it to non-volatile storage during a shutdown process, using a power hold-up module, and performs a binary search to find the latest valid version during startup to resume operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If meta data is stored only in volatile memory, then data access speed is improved, but data loss occurs during sudden power loss
Solution Approach 1:
The patent maintains copies of meta data in both volatile memory (for fast access during normal operation) and non-volatile storage media (for data protection during power loss). The controller periodically copies meta data from volatile memory to non-volatile storage, ensuring that a valid copy persists even when power is suddenly lost.
2Reliability
If meta data is copied to non-volatile storage during shutdown, then data integrity is improved, but startup time increases due to need to recover and search for latest version
Solution Approach 1:
The patent performs preliminary actions during normal operation by maintaining version information and validity flags for meta data copies in non-volatile storage. During startup, the controller can quickly identify the latest valid version using pre-stored version metadata rather than searching through all copies, significantly reducing startup time while ensuring data integrity.
3Ease of operation
If all meta data versions are retained in non-volatile storage, then recovery of latest valid version is simplified, but storage space consumption increases
Solution Approach 1:
The patent creates selective copies of meta data at different points in time, keeping multiple versions in non-volatile storage with associated version information. This allows the system to retain enough historical versions for recovery purposes while managing storage space through selective copying rather than retaining all possible versions indefinitely.
Data Source
AI summary
A computer system having a host coupled to a storage device via a peripheral component interconnect express bus. The host communicates with the storage device in accordance with a non-volatile memory host controller interface specification. The storage device stores versions of meta data sequentially in a portion of a volatile memory that is protected against power failure using a power hold-up module. In response to a sudden power loss, the power hold-up module provides sufficient energy to support operations to copy the content from the portion of the volatile memory into a non-volatile memory. During a startup process, the content is retrieved from the non-volatile memory; and a binary search is performed to locate, within the content, the latest, valid version of the meta data to continue operations interrupted by the power loss.