Virtual Cache Management for Auxiliary Memory Data Integrity
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Solution Overview
Problem
The existing computer systems face performance bottlenecks due to slow data retrieval from disk drive memory, which can be alleviated by using auxiliary memory as cache, but existing caching techniques are inefficient and may result in data loss when removable auxiliary memory is disconnected.
Innovation Solution
Implementing a caching system that uses auxiliary memory, such as flash memory, to store 'clean' pages and ensuring data integrity by maintaining backups, and using virtual page identifiers to optimize caching, allowing for efficient data management and secure, compressible storage with encryption and authenticity verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If auxiliary memory is used as cache memory, then data retrieval speed is improved, but data loss occurs when the auxiliary memory is disconnected
Solution Approach 1:
The patent segments cached pages into two categories: clean pages (not modified since loading) and dirty pages (modified). Clean pages are cached on removable auxiliary memory, while dirty pages are kept only in main memory. This segmentation resolves the contradiction by allowing fast caching of safe data while protecting critical modified data from loss.
Solution Approach 2:
The system performs preliminary actions by flushing dirty pages to the source storage before disconnecting the auxiliary memory, or by tracking which pages are clean versus dirty. This preliminary identification and handling of page states prevents data loss while maintaining the performance benefits of caching.
2Quantity of substance
If physical address caching is used, then data can be stored on auxiliary memory, but cache memory space is used inefficiently
Solution Approach 1:
The patent transitions from physical address-based caching to virtual address-based caching. By operating in the virtual address space dimension rather than the physical address dimension, the system can identify and cache only the specific virtual pages that processes actually need, rather than caching entire physical blocks. This dimensional shift resolves the contradiction by enabling precise control over what is cached.
Solution Approach 2:
The system applies local quality by caching only the specific virtual pages that are actually needed by processes, rather than uniformly caching entire physical blocks. Each virtual page is evaluated individually based on its actual usage requirements, allowing efficient use of cache space by storing only relevant data.
3Ease of operation
If entire data blocks are cached, then data retrieval is simplified, but most of the block remains unused
Solution Approach 1:
The patent segments data into individual virtual pages rather than caching entire physical blocks. This segmentation allows the system to cache only the specific pages that processes need, rather than retrieving and caching entire blocks. The segmentation resolves the contradiction by enabling precise control over cache content while maintaining efficient data retrieval for the needed pages.
4Quantity of substance
If disk drive defragmentation is performed, then disk space is freed, but cache management becomes complicated
Solution Approach 1:
The patent resolves the defragmentation complexity by operating in virtual address space rather than physical address space. Since virtual pages are identified by their logical addresses rather than physical locations, the system automatically adapts to physical rearrangements on disk without requiring complex cache management changes. The virtual-to-physical mapping layer isolates the cache from physical disk reorganization.
Data Source
AI summary
A method and apparatus for managing the caching of data on an auxiliary memory of a computer. Pages of data may be cached on an auxiliary memory, such as a flash memory, at a virtual level using an identifier that does not involve a physical address of the pages on a memory. Pages may be cached on auxiliary memory that may be removable from the computer, e.g., by unplugging the memory from the computer. Page data may be encrypted and/or compressed on the auxiliary memory. An authentication indicator may be used to verify the accuracy of cached data in the case of an interrupted connection to the auxiliary memory, e.g., as a result of computer power down, hibernation, removal of the memory from the computer, etc.