Aggregating ALUA Port States Across Storage Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current data storage systems, particularly those using ALUA and MPIO, do not support host discovery of port status for replicated volumes presented by multiple storage arrays configured for active-active remote replication, limiting load balancing and optimization across multiple target port groups.
Innovation Solution
A system where a first storage array combines the target port states of itself and a second storage array to generate a logical target port group state, which is then sent to the host, allowing for optimized port selection and load balancing across interconnected storage arrays by translating port IDs into unique IDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple storage arrays present replicated volumes to a host, then data redundancy and availability are improved, but the host cannot discover port status across multiple arrays due to ALUA limitations
Solution Approach 1:
The patent combines port status information from multiple storage arrays into a single unified target port group state that the host can query. The first storage array aggregates ALUA port states from itself and the second storage array, creating a consolidated view that allows the host to discover all port statuses across both arrays through a single interface, resolving the ALUA limitation of one TPG per array.
Solution Approach 2:
The first storage array acts as an intermediary that mediates between the host and the second storage array. It receives TPG status queries from the host, forwards them to the second storage array, obtains the port states, and combines them with its own port states before returning the unified state to the host, enabling indirect port status discovery across arrays.
2Reliability
If a single TPG is used per storage array in accordance with ALUA standards, then protocol compliance is maintained, but ports from multiple arrays cannot be included in the same TPG for unified management
Solution Approach 1:
The first storage array's target port group is enhanced to serve multiple functions: it represents both its own local ports and the remote ports of the second storage array. This unified TPG provides universal access points that the host can use to manage and monitor ports across both storage arrays, enabling multi-array port management while maintaining single TPG structure.
3Loss of information
If multiple TPGs are used to represent different storage arrays, then port status can be represented, but MPIO cannot perform load balancing across multiple TPGs
Solution Approach 1:
The patent merges the port status information from multiple TPGs into a single unified target port group state. By consolidating the port states from both storage arrays into one logical TPG representation, the host's MPIO driver can perform load balancing operations across all ports as if they belonged to a single TPG, restoring load balancing capability while maintaining complete port status information.
Data Source
AI summary
In response to a target port group state query from a host, the storage arrays that present a replicated volume to the host aggregate port group state of the storage arrays into a single logical target port group state that is provided to the host. The storage array that receives the query from the host may prompt other storage arrays to provide target port group state and combine the responses from all storage arrays. Port IDs may be translated into unique port IDs so that the logical target port group state does not include repeated port IDs.