Active-Active Storage Address Assignment via Host-Based LUN ID
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Solution Overview
Problem
In active-active storage systems, address inconsistencies between level 2 LUNs can occur due to different address information, leading to data discrepancies when one data center fails and services are switched to another, causing potential data loss and inconsistency.
Innovation Solution
An address assignment apparatus is introduced to ensure address consistency between level 2 LUNs by obtaining a valid address from the assignable-address sets of both storage arrays and sending it to both arrays, allowing seamless data transfer and synchronization between active-active LUNs, even when one link fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If addresses of level 2 LUNs in two data centers are different, then each storage array can independently manage its own LUN addressing, but the second data center cannot find the corresponding LUN in active-active pairing, causing data inconsistency
Solution Approach 1:
The patent changes the address parameter from storage array-specific addresses to host-based LUN IDs. By using LUN IDs that are assigned by the host and recognized by both storage arrays, the system maintains independent address management capability while ensuring that both data centers can correctly identify and access the paired LUNs, thus resolving the data consistency issue.
Solution Approach 2:
The patent introduces a universal addressing mechanism where LUN IDs serve multiple functions: they are assigned by the host, used by both storage arrays to identify paired LUNs, and maintain consistency across active-active configurations. This universal LUN ID system replaces the need for separate address management schemes in each data center.
2Reliability
If an address assignment apparatus is introduced to ensure address consistency, then data consistency between active-active LUNs is achieved, but the system complexity increases
Solution Approach 1:
The host performs the address assignment function itself by assigning LUN IDs to level 2 LUNs. The storage arrays do not need external address assignment apparatus because they receive the LUN ID information directly from the host along with I/O commands. This self-service approach eliminates additional address management devices while maintaining address consistency.
Solution Approach 2:
The host acts as an intermediary that assigns LUN IDs and communicates them to both storage arrays. Instead of introducing a separate address assignment apparatus, the existing host system serves as the mediator that ensures address consistency by assigning and distributing the same LUN ID to paired LUNs in both data centers.
Data Source
AI summary
A method of labeling logic number units in a storage system results in the use of the same label for related LUNs in different storage arrays. A first storage array includes a first source logical unit number LUN, the second storage array includes a first target LUN, and the first source LUN and the first target LUN are a pair of active-active LUNs. The first storage array sends an assignable-address set of selectable labels for the first source LUN to the address assignment apparatus. The second storage array sends an assignable-address set of selectable labels for the first target LUN to the address assignment apparatus. The address assignment apparatus selects a label that is in both assignable-address sets of the first source LUN and first target LUN, and assign that selected label to both LUNs. Thereafter, the address assignment apparatus sends the selected label to the first storage array and the second storage array for identifying both the first source LUN and the first target LUN.