Concurrent Tape Drive Access via SCSI Persistent Reservation
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Solution Overview
Problem
In large to mid-sized organizations, single nodes often lack sufficient Input/Output (I/O) bandwidth to efficiently utilize tape drives for data backup, leading to inefficient backup processes and disruptions due to insufficient transfer rates, which result in wasted tape space and latency.
Innovation Solution
A method and apparatus that enable multiple nodes to concurrently access a tape drive using Small Computer System Interface (SCSI) persistent reservation commands, allowing for shared or exclusive write access, coordinated by a control node to optimize data transfer rates and prevent disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single node is used to access the tape drive, then the node can control the backup process, but the I/O bandwidth is insufficient to maintain high transfer rates
Solution Approach 1:
The patent segments the backup process by allowing multiple nodes to concurrently access the tape drive through shared write support. Each node can independently write data to the tape drive simultaneously, dividing the backup workload across multiple nodes rather than relying on a single node's limited I/O bandwidth.
Solution Approach 2:
The patent merges the backup operations of multiple nodes by enabling them to all access the same tape drive concurrently. The storage subsystem coordinates these multiple write operations, combining their data streams into a single tape output, thereby aggregating the bandwidth capacity of multiple nodes.
2Reliability
If the data transfer rate falls below the minimum threshold, then the tape drive can operate, but the tape must be stopped and rewound causing latency
Solution Approach 1:
The patent ensures continuous useful action by enabling multiple nodes to write data to the tape drive simultaneously at high rates. This maintains the tape drive's optimal operating speed continuously, preventing the need to stop and rewind, thereby eliminating latency and maintaining uninterrupted backup operation.
3Productivity
If multiple nodes concurrently access the tape drive, then the backup rate increases, but coordination complexity increases
Solution Approach 1:
The patent introduces a storage subsystem as an intermediary that mediates between multiple nodes and the tape drive. This intermediary handles the coordination complexity by managing shared write access, ensuring proper data stream separation and recombination, thereby enabling high-speed concurrent access without requiring complex direct coordination between nodes.
4Device complexity
If a single node streams data to the tape drive, then the setup is simple, but the tape drive cannot be accessed by other nodes simultaneously
Solution Approach 1:
The patent implements universality by enabling the tape drive to be accessed by multiple nodes simultaneously for backup operations. The storage subsystem supports shared write access, allowing any node in the system to initiate a backup operation on the tape drive without requiring exclusive access, thereby providing multi-functional access capability.
Data Source
AI summary
Embodiments of the present invention comprise a method and apparatus for performing data backup from multiple nodes of a computer network. In one or more embodiments, the method of performing a data backup from multiple nodes of a computer network comprising generating a control message within a control node and, in response to the control message, enabling two or more nodes of the multiple nodes to access a tape drive concurrently.