Disk Buffer Controller Optimizing Write Queuing via Media Cache Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic disk devices face challenges in efficiently managing and queuing write data during power failures, as existing power loss protection (PLP) functions rely on nonvolatile memory capacity, limiting the amount of data that can be assuredly written to disk and potentially degrading write performance due to caching operations.
Innovation Solution
The magnetic disk device employs a controller to compare processing amounts for saving write data to a media cache area and a user area, determining whether to save data to the media cache area based on Input Output Per Second (IOPS) loss and improvement values, thereby optimizing data storage and preventing performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If write data is saved to nonvolatile memory for power loss protection, then data integrity is improved, but write performance deteriorates due to limited memory capacity and caching operations
Solution Approach 1:
The patent segments the disk storage into multiple regions: a first region (media cache area) for temporary write data storage and a second region for final data storage. This segmentation allows the system to queue write commands in the first region without immediately writing to nonvolatile memory, thereby improving write performance while maintaining data integrity through the PLP function.
Solution Approach 2:
The patent introduces a media cache area as an additional storage dimension between the buffer and nonvolatile memory. This creates a multi-layered storage architecture that virtually increases the PLP amount by providing an intermediate staging area, allowing more write commands to be queued without directly impacting nonvolatile memory capacity.
2Reliability
If the PLP amount is increased by using nonvolatile memory capacity, then data assurance capability is improved, but the queuing amount of write commands is limited
Solution Approach 1:
The patent creates a media cache area as an additional storage dimension that virtually increases the PLP amount. This media cache area serves as an intermediate storage layer that can hold write data without consuming nonvolatile memory capacity, thereby increasing the queuing amount of write commands while maintaining data assurance capability.
3Speed
If write data is cached in volatile memory, then write speed is improved, but data loss risk increases during power failure
Solution Approach 1:
The patent implements preliminary action by saving write data to the media cache area (first region) before potential power loss occurs. This intermediate storage layer ensures that data is preserved in a nonvolatile manner while still allowing fast write operations, eliminating data loss risk associated with volatile memory caching.
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk including a first region and a second region, a head configured to record write data to the disk, a buffer configured to store the write data up to a first capacity, and a controller configured to obtain a first processing amount based on a time to save the write data to the first region by the head and a second processing amount improved by saving the write data from the buffer to the first region, compare the first processing amount with the second processing amount, and determine whether the write data should be saved to the first region, based on a result of the comparison between the first processing amount and the second processing amount.