PCIe Switching Unit for Distributed Disk Array Control
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Solution Overview
Problem
Conventional IP SAN systems face issues such as excessive service load on the control unit leading to delays or failures, limited expansion capacity due to routing table limitations, and long port-to-port delays, which hinder efficient disk access and data transfer.
Innovation Solution
Implementing a PCIe switching unit between the processing and control units in both master and slave disk arrays, allowing for distributed control and increased address space mapping, thereby reducing processing delays and expanding disk capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple slave disk arrays are cascaded to expand disk capacity, then the disk capacity is expanded, but the control unit of the master disk array experiences excessive service load leading to delays or failures
Solution Approach 1:
The patent divides the centralized control function into distributed control units. Each slave disk array is equipped with its own control unit that can independently process access commands, rather than all commands being handled by the master disk array's control unit. This segmentation of control functions distributes the service load and prevents any single control unit from becoming overloaded.
Solution Approach 2:
The patent introduces expanders as intermediary devices between the control units and disk arrays. These expanders manage command routing and coordination, reducing the direct burden on control units by handling lower-level communication and control tasks.
2Adaptability or versatility
If conventional expanders with routing tables are used to connect disk arrays, then disk arrays can be connected, but the routing table limitations restrict expansion capacity
Solution Approach 1:
The patent transitions from a two-dimensional routing table structure (limited by row-column constraints) to a three-dimensional crossbar switching architecture. This dimensional change allows multiple simultaneous connections and pathways, dramatically increasing the expansion capacity without being constrained by traditional routing table limitations.
Solution Approach 2:
The patent implements multiple control units across different disk arrays, creating redundant control capabilities. Each control unit can independently manage its local disk array, providing backup and load distribution, which effectively overcomes the single-point limitation of conventional routing table-based systems.
3Quantity of substance
If conventional IP SAN systems are used for disk access, then data storage is achieved, but port-to-port delays are long reducing access speed
Solution Approach 1:
The patent extracts the control unit from the master disk array and distributes it to each slave disk array. This extraction eliminates the need for commands to traverse back through the master disk array's control unit, significantly reducing port-to-port delays and improving data access speed.
Solution Approach 2:
The patent pre-establishes direct control connections between each slave disk array's control unit and its local disks. This preliminary configuration of distributed control paths allows commands to be executed locally without waiting for centralized processing, reducing access latency.
Data Source
AI summary
The present invention discloses a method for accessing a target disk and a system for expanding disk capacity. A processing unit of a master disk array sends a command or data to a PCIe switching unit of the master disk array upon receipt of the command or data; the PCIe of the master disk array sends the received command or data to a control unit in a corresponding disk array according to an address of a target disk indicated in the command or data; the control unit in the corresponding disk array sends the received command or data to the target disk that is directly connected to the control unit. The present invention also discloses a master disk array and a slave disk array.