ZCAT Storage Optimization in Data Storage Controllers
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Solution Overview
Problem
The existing method of storing a CAT table in a host memory buffer (HMB) during data storage device operations is inefficient due to associated overhead, outdated information, and large storage requirements.
Innovation Solution
A data storage device with a controller that determines the workload type and persistence/temperature of a compressed logical to physical translation table (ZCAT), storing a portion in RAM and the remaining portion in HMB, allowing the HMB portion to update out-of-date entries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the CAT table is stored entirely in the HMB, then access speed is improved, but storage overhead and management complexity increase
Solution Approach 1:
The patent divides the CAT table into two segments: a first portion stored in the HMB for fast access during normal operations, and a second portion stored in the flash memory as a backup. This segmentation allows the system to enjoy the speed benefits of HMB storage while reducing the complexity of managing a complete HMB-based CAT table, as the flash memory portion serves as a simplified backup mechanism.
2Loss of time
If the CAT table is stored in the HMB, then access time is reduced, but data freshness deteriorates due to outdated information
Solution Approach 1:
The patent introduces the flash memory as an intermediary backup storage for the CAT table. The HMB stores the active CAT table for fast access, while the flash memory maintains a backup copy that serves as the source of truth. This intermediary backup mechanism ensures data freshness without compromising access time, as the system can refresh the HMB portion from the flash memory backup when needed.
3Loss of time
If the CAT table is stored in the HMB, then read latency is reduced, but storage space requirements increase
Solution Approach 1:
The patent segments the CAT table storage between HMB and flash memory, with only the first portion residing in the HMB at any given time. This segmentation reduces the storage space burden on the HMB compared to storing the entire CAT table there, while still achieving reduced read latency for the active portion. The flash memory accommodates the second portion, distributing the storage space requirements across both media.
Data Source
AI summary
A data storage device includes a memory device, a random access memory (RAM) device, and a controller coupled to the memory device and the RAM device. The controller is configured to determine a workload type of the data storage device, determine to store at least a portion of a compressed logical to physical translation table (ZCAT) in the RAM device based on the workload type, and utilize a remaining portion of the RAM device to perform background operations. The controller is further configured to determine a persistence or temperature of the ZCAT, where the portion of the ZCAT stored to the RAM device is based on the persistence and/or the temperature of the ZCAT. The remaining portion of the ZCAT is stored in the HMB, where the remaining portion may update any out-of-date ZCAT entries.