Magnetic Tape Backhitch Control via Next Transaction Size
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for controlling writing in magnetic tape units struggle to accurately determine the size of the next transaction during backhitch operations, leading to inefficiencies and increased backhitch time due to undefined optimal starting positions for acceleration to the next definitive velocity.
Innovation Solution
A method that involves receiving the size of the next transaction from the host before starting the backhitch operation, calculating the time and position for backhitch based on this size, and adjusting the tape velocity accordingly to minimize backhitch time and optimize writing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If backhitch operations are performed with fixed velocity patterns, then the tape drive can maintain simple control logic, but the writing performance decreases due to excessive backhitch time when next transaction size is unknown
Solution Approach 1:
The host performs preliminary action by notifying the tape drive of the next transaction size before the backhitch operation starts. This advance information allows the tape drive to calculate and prepare the optimal backhitch time and rewind distance, eliminating the need for fixed velocity patterns and reducing unnecessary backhitch time while maintaining simple control logic.
2Productivity
If the tape velocity is optimized based on next transaction size, then the overall writing performance improves, but the control system complexity increases due to dynamic velocity calculation
Solution Approach 1:
The host acts as an intermediary by providing the next transaction size information to the tape drive. This simple information exchange enables the tape drive to perform dynamic velocity calculation and optimization without requiring complex internal sensors or feedback mechanisms, thus improving overall writing performance while keeping the control system relatively simple.
3Ease of operation
If the tape is rewound to a fixed position for backhitching, then the control logic remains simple, but unnecessary rewind distances increase when the next transaction is small
Solution Approach 1:
The tape drive changes the rewind distance parameter dynamically based on the next transaction size provided by the host. Instead of using a fixed rewind position, the system adjusts the rewind distance to match the actual needs of the next transaction, reducing unnecessary rewind operations while maintaining relatively simple control logic through straightforward parameter adjustment.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
[Object] To provide a method for controlling writing for reducing the effects of a backhitch that occurs when a synchronous command is issued in a writing operation in a magnetic tape unit. [Solving Means] A method for controlling writing for a tape recorder that is connected to a host and sequentially records, as a transaction, a plurality of records that are transferred from the host and stored in a buffer is provided. The control method includes a step of receiving a synchronous command for a first transaction from the host, a step of, in response to the synchronous command, sequentially writing the plurality of records stored in the buffer to a tape as the first transaction, a step of receiving the size of a second transaction following the first transaction from the host, a step of calculating time for a backhitch associated with an operation of the synchronous command for the first transaction on the basis of the size, and a step of performing the backhitch on the basis of the time for the backhitch. In the control method, the step of receiving the size receives the size of the second transaction at least before rewinding in the backhitch is started. Moreover, in the control method, the step of calculating the time for the backhitch minimizes the time for the backhitch on the basis of the size. The present invention also includes a tape recorder that implements the control method and a tape recording system that includes the host and the tape recorder connected to the host. In the present invention, since the distance over which a tape is rewound at the time of backhitching and the writing velocity can be selected in a manner that depends on the size of the next transaction, an advantageous effect in which the overall performance of writing can be improved is achieved.