iSCSI Acceleration Device Reducing WAN Latency
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Solution Overview
Problem
iSCSI data transfers across long distance networks experience significant latency due to the time required for commands, data, and responses to complete a round trip, which impedes the adoption of iSCSI for storage networks over Wide Area Networks.
Innovation Solution
An acceleration device is placed in the communication path between the iSCSI initiator and target, intercepting requests and generating anticipated responses to reduce latency by allowing the initiator to continue data transfers without waiting for the target's response, thereby acting as a proxy to expedite data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If iSCSI data transfers are implemented across long distance networks, then storage network coverage is expanded, but latency increases significantly
Solution Approach 1:
The patent introduces an intermediary device positioned between the iSCSI initiator and target that intercepts requests and generates anticipated responses. This intermediary acts as a proxy that locally simulates target responses, thereby mediating the interaction between initiator and remote target to reduce round-trip latency while enabling long-distance network coverage.
Solution Approach 2:
The acceleration device performs preliminary action by generating anticipated responses before the actual target processing completes. By predicting and issuing responses in advance based on the request type and pre-established patterns, the system eliminates waiting time for remote target responses, effectively performing the response generation action beforehand.
2Productivity
If round trip time for iSCSI commands and responses is reduced, then data transfer performance improves, but network distance constraints limit deployment flexibility
Solution Approach 1:
The intermediary acceleration device resolves the conflict between performance and deployment flexibility by locally generating responses that simulate remote target behavior. This allows high-speed data transfer performance to be achieved at the intermediary location while the actual target can remain at any remote distance, effectively decoupling performance requirements from physical proximity constraints.
Solution Approach 2:
The system creates a copy of the target's response generation capability at the intermediary location. By replicating the essential response functions locally rather than requiring direct communication with the remote target, the system achieves low-latency performance while allowing the original target to be deployed anywhere on the network without performance degradation.
3Reliability
If iSCSI protocol maintains strict request-response sequencing, then data integrity is ensured, but transfer speed decreases due to latency
Solution Approach 1:
The intermediary device maintains data integrity by acting as a protocol-compliant mediator that generates responses following the same sequencing rules as the actual target. It ensures that request-response pairs maintain proper ordering and acknowledgment patterns, thereby preserving data integrity guarantees while eliminating the speed-reducing latency of remote round-trip communication.
Solution Approach 2:
By copying the target's response generation logic and behavior patterns at the intermediary location, the system reproduces the exact protocol sequencing and data integrity mechanisms that would occur with direct target communication. This allows the initiator to receive responses in the correct sequence with the same reliability guarantees, but at much higher speeds due to local response generation.
Data Source
AI summary
An Internet Small Computer Systems Interface (iSCSI) distance acceleration device accelerates data transfers between an iSCSI initiator and an iSCSI target over a network, such as the Internet or a wide area network (WAN). The acceleration device resides in a communication path between the iSCSI initiator and the iSCSI target. The acceleration device receives an iSCSI protocol data unit (PDU) targeted to the iSCSI target by the iSCSI initiator. The acceleration device forwards the iSCSI PDU over the network to the iSCSI target and transmits a response to the iSCSI PDU that anticipates a response to be generated by the iSCSI target upon receiving the iSCSI PDU.