SMR Disk Write Buffering for Random-Access Performance
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Solution Overview
Problem
Hard disk drives (HDDs) using shingled magnetic recording (SMR) face challenges in write performance due to frequent requests for small-sized or random-access data writing, which degrade performance in embedded systems requiring real-time capabilities.
Innovation Solution
Implementing a delayed writing mechanism that accumulates data in a volatile memory buffer until it reaches a threshold, allowing for bulk sector-based writing to the nonvolatile SMR HDD, reducing fragmented sectors and random access requests, and optimizing file management to ensure real-time performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If data is written to SMR HDD in small units or random access, then flexibility and responsiveness are improved, but write performance degrades
Solution Approach 1:
The system performs preliminary actions by accumulating data in a volatile memory buffer before writing to the SMR HDD. Data is collected and pre-processed in the buffer until a threshold is reached, then bulk written to the disk in sequential order. This preliminary accumulation phase allows the system to maintain flexibility in accepting individual write requests while ensuring high-performance bulk writes to the SMR drive.
2Productivity
If data is accumulated in a buffer before writing, then write performance is improved, but memory usage increases
Solution Approach 1:
The system dynamically adjusts the buffer threshold parameter to optimize between write performance and memory usage. By changing the threshold value at which buffer contents are flushed to disk, the system can adapt to different workload conditions and available memory resources, balancing performance gains against memory consumption.
3Productivity
If sequential writing is used in SMR HDD, then write performance is improved, but adaptability to random access requests decreases
Solution Approach 1:
The volatile memory buffer acts as an intermediary between random access write requests from the system and the sequential writing requirement of the SMR HDD. Individual write requests are accepted and stored in the buffer without immediate disk access, allowing the buffer to accumulate data suitable for sequential bulk writes. This intermediary layer decouples the flexible request acceptance from the performance-optimized sequential write execution.
Data Source
AI summary
An information processing apparatus includes a nonvolatile memory and circuitry. The nonvolatile memory stores data written using shingled magnetic recording, in which tracks are partially arranged one over another in a radial direction. The circuitry is to instruct the nonvolatile memory to write the data in units of sectors, additionally write the data to a data writing area of the nonvolatile memory, create, on a volatile memory, a buffer for delayed writing in which the data to be written to the data writing area is temporarily held, and write the data in the buffer for delayed writing to the nonvolatile memory in a case that a total amount of data accumulated in the buffer for delayed writing exceeds a threshold value.