Storage Controller Mapping Mechanism for Direct Disk Access
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Solution Overview
Problem
Existing data processing systems face performance and power consumption overheads due to the need for strict data security and isolation, where all data accesses must go through the operating system or hypervisor, leading to inefficiencies in virtual machines and physical accelerators accessing disk storage.
Innovation Solution
A mapping mechanism within a storage controller translates offsets to physical addresses, allowing devices and virtual machines to access on-disk data directly, bypassing the CPU and management software, and using shadow controllers to enforce access permissions and facilitate low-latency, high-bandwidth access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data access requests are routed through the operating system and CPU for security enforcement, then data security and isolation are maintained, but performance overhead and power consumption increase substantially
Solution Approach 1:
The patent introduces a mapping mechanism as an intermediary component within the disk controller that translates logical block addresses to physical addresses without requiring CPU or operating system intervention. This intermediary structure enables direct device-to-disk access while maintaining security boundaries, resolving the contradiction between security enforcement and performance efficiency
Solution Approach 2:
The patent extracts the address translation function from the operating system/CPU path and relocates it to a dedicated mapping mechanism within the disk controller. By taking out this critical function from the high-overhead software path and placing it in hardware, the system achieves both security (through controlled access) and performance (through direct hardware translation)
2Reliability
If virtual machines use emulation or paravirtualization to access storage, then security and isolation are provided by the hypervisor, but every request incurs performance overhead due to hypervisor intervention
Solution Approach 1:
The patent enables virtual machines to access storage directly through the mapping mechanism without requiring hypervisor service for each request. The mapping mechanism autonomously handles address translation and access control, allowing VMs to self-serve their storage needs without hypervisor mediation, thereby eliminating the time loss associated with hypervisor intervention while maintaining security isolation
3Speed
If physical accelerators directly access the peripheral device interconnect and disk controllers, then data access speed improves, but data protection and isolation must still route through the CPU running the operating system
Solution Approach 1:
The patent merges the address translation function with the disk controller hardware, creating an integrated mapping mechanism that operates within the controller itself. This consolidation allows physical accelerators to maintain direct high-speed access to the disk while the integrated mapping mechanism handles protection and isolation natively within the controller, eliminating the need for CPU-mediated access control and simplifying the overall architecture
Data Source
AI summary
Data access in a storage device managed by a storage controller is carried out by receiving in the storage controller offsets in objects directly from a plurality of requesting entities of a computer system. The computer controls a mapping mechanism operated by the storage controller, wherein the mapping mechanism relates the offsets in the objects into physical addresses of the data on the storage device, and wherein the data is accessed at the physical addresses.