New File Creation Cache for Composite Storage Devices
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Solution Overview
Problem
Existing file systems struggle to efficiently manage storage in composite devices consisting of fast and slow storage devices, as they often run out of space on the fast storage device, leading to inefficient allocation of new files across both devices.
Innovation Solution
A method that uses a mapping table to differentiate between new and existing files, prioritizing writes to the fast storage device while reserving space by allocating existing files to the slow storage device when necessary, and migrating less-used files to free up space on the fast device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If new files are allocated to the fast storage device, then storage performance is improved, but the fast storage device will eventually run out of space
Solution Approach 1:
The patent segments the storage system into fast and slow storage devices, with the fast device dedicated to new files and the slow device for existing files. The mapping table segments the address space to track which device stores which files, allowing the system to maintain high performance for new allocations while preserving space on the fast device through automatic segmentation of storage responsibilities.
Solution Approach 2:
The patent performs preliminary actions by pre-allocating new files to the fast storage device before the slow device is involved. The mapping table is proactively updated to reflect this allocation, and the system proactively migrates existing files to the slow device when space is needed, preventing the fast device from running out of space before performance can be optimized.
2Speed
If the fast storage device is used for all new files, then access speed is improved, but device complexity increases due to space management
Solution Approach 1:
The mapping table serves as an intermediary data structure that simplifies space management complexity. It automatically tracks file locations across fast and slow storage devices, translating high-level allocation requests into device-specific operations. This intermediary layer shields the system from the complexity of direct space management while maintaining fast access speeds for new files.
3Ease of operation
If space is reserved on the fast storage device, then new file creation is facilitated, but the overall storage capacity utilization decreases
Solution Approach 1:
The patent merges the fast and slow storage devices into a unified logical volume with a single address space. The mapping table enables seamless combining of both devices, allowing new files to be created on the fast device while existing files reside on the slow device. This merging approach facilitates easy new file creation on fast storage while maintaining high overall capacity utilization by actively using both devices.
Data Source
AI summary
In one embodiment, a new file creation cache is reserved on a fast storage device that is part of a composite storage device that also includes a slow storage device; the composite storage device is treated as a single logical volume (or a plurality of logical volumes) by a file system which maintains a mapping table that is used to determine whether the write operation is for a new file. If the write operation is for a new file, the file system attempts to write the new file to the fast storage device. If the write operation is not for a new file, the mapping table specifies which device is used for the write operation.