Link Rate Arbitration via AIP Delay for PHY Resource Utilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Data storage systems face challenges in managing connections when an initiator requests a link rate that is not available among the phys, leading to inefficient resource utilization and frequent connection retries.
Innovation Solution
An expander with a link manager that initiates an arbitration in progress (AIP) delay when no phys with the selected link rate or higher are available, scans for available phys during this delay, and either completes the connection if a suitable phy becomes available or returns a rejection message, thereby optimizing resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the link manager immediately returns a rejection message when no phy with the selected link rate is available, then the response time is fast, but the resource utilization is poor and connection retries increase
Solution Approach 1:
The link manager performs a preliminary check of phy availability before immediately rejecting the connection request. By proactively checking whether any phy will become available during the AIP delay period and reserving it in advance, the system prevents future connection failures and reduces retries, thus improving resource utilization without significant time loss.
Solution Approach 2:
The system dynamically adjusts its response based on real-time phy availability status. Instead of a static immediate rejection, the link manager evaluates the current arbitration state and phy allocation status, then decides whether to reject immediately or initiate an AIP delay with phy reservation, optimizing both response time and resource utilization dynamically.
2Productivity
If the link manager initiates an arbitration in progress (AIP) delay to wait for phy availability, then the resource utilization improves, but the connection establishment time increases
Solution Approach 1:
The link manager performs a preliminary evaluation during the AIP delay to determine if a phy will become available. By proactively checking phy status and reserving available phys before the delay expires, the system avoids unnecessary waiting and reduces the effective connection establishment time while maintaining high resource utilization.
Solution Approach 2:
When a phy becomes available during the AIP delay, the link manager immediately completes the connection request without waiting for the full delay period to expire. This rushing through of the connection establishment process minimizes the actual waiting time while still benefiting from the phy reservation mechanism, thus improving connection speed without sacrificing resource utilization.
3Reliability
If the link manager reserves a phy during AIP delay, then the connection success rate improves, but the device complexity increases
Solution Approach 1:
The phy reservation mechanism is integrated into the existing link manager's arbitration logic. The link manager uses its existing knowledge of phy status and arbitration state to automatically determine reservation needs, eliminating the need for separate complex reservation management systems and keeping the added complexity minimal while improving connection success rate.
Data Source
AI summary
The disclosure is directed to a system and method for managing connections across a plurality of phys including at least one phy having a first link rate and at least one phy having a second link rate. At least one connection request including a selected link rate is received from an initiator. An arbitration in progress (AIP) delay is provided when at least one phy having the selected link rate or higher is not available. During the AIP delay, a link manager continues to check for a phy having the selected link rate or higher. The link manager completes the connection request if a phy having the selected link rate or higher becomes available before the AIP delay ends.