Translation Table Backup Strategy for Boot Time and Write Amplification
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Solution Overview
Problem
In storage systems, the existing methods for backing up and recovering logical-to-physical translation tables consume excessive system bandwidth and increase write amplification due to the large size of the translation table, which needs to be updated frequently, leading to inefficiencies in boot time and storage throughput.
Innovation Solution
The proposed solution involves saving a baseline version of the translation table in non-volatile memory and incremental updates, allowing adaptive control of the number of incremental updates based on the host's write activity profile and boot time constraints, thereby optimizing the ratio of baseline bulks to incremental updates to meet boot time specifications while reducing write amplification and improving storage throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire translation table is backed up frequently in non-volatile memory, then data reliability is improved, but write amplification increases and system bandwidth is consumed
Solution Approach 1:
The translation table is divided into multiple segments or chunks. Instead of backing up the entire table frequently, only specific segments are backed up based on their update frequency and importance. This segmentation allows selective backup of critical portions while reducing overall write operations to non-volatile memory.
Solution Approach 2:
The patent extracts and identifies the most critical or frequently accessed portions of the translation table that require reliable backup. By taking out only these essential segments for frequent backup while leaving less critical segments to be updated less frequently, the system achieves reliable data protection without the penalty of backing up the entire table.
2Reliability
If the entire translation table is restored during boot, then data completeness is ensured, but boot time increases
Solution Approach 1:
The translation table restoration process is segmented into priority levels. Critical segments are restored first to enable basic system functionality, while less critical segments are restored subsequently or deferred. This segmented restoration ensures data completeness while significantly reducing the time required for full table recovery during boot.
Solution Approach 2:
The patent implements preliminary actions during normal operation by pre-loading or pre-restoring critical translation table segments into memory before they are actually needed. This preliminary preparation ensures that essential translation data is available quickly during boot, reducing overall restoration time while maintaining data completeness.
3Speed
If incremental updates are increased to reduce boot time, then boot speed is improved, but write amplification increases
Solution Approach 1:
The patent implements a dynamic strategy where the number and frequency of incremental updates are adjusted based on system conditions, workload characteristics, and boot time requirements. This dynamic approach optimizes the balance between boot speed and write amplification by adapting the update frequency to actual needs rather than using a fixed schedule.
Solution Approach 2:
The system changes key parameters such as incremental update frequency, segment size, and backup intervals based on observed workload patterns and performance metrics. By dynamically adjusting these parameters, the system can reduce boot time when necessary while minimizing write amplification during normal operation, achieving an optimal balance between the two competing requirements.
Data Source
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AI summary
An apparatus includes an interface and a processor. The interface is configured to communicate with a non-volatile memory. The processor is configured to hold a translation table that maps between logical addresses and respective physical addresses in the non-volatile memory, to back-up to the non-volatile memory a baseline version of the translation table in one or more bulks, to additionally back-up to the non-volatile memory one or more incremental updates, which specify changes relative to the baseline version of the translation table caused by subsequent storage operations, to determine a maximal number of the incremental updates that, when recovered together with the baseline version from the non-volatile memory and replayed in the processor, meets a target recovery time of the translation table, and to set a number of the backed-up incremental updates to not exceed the maximal number.