Data storing system and transmission control method

Abstract

Data storing system and transmission control method. The data storage system 1 comprises tape drives 21 to 23 operable to read and write data transmitted via the SCSI bus 112 from and on a tape in parallel and a host PC 4 for controlling data transmission to the SCSI bus. The host PC 4 includes a data access control unit 41 operable to calculate a bus reconnect timing that makes it possible to avoid stopping tape writing or reading even when any one of the respective drive drives 21 to 23 waits for the time when the other tape drives finish data transmitting after it reaches a bus reconnect timing based on the tape drive information '(the number of drive units, a data transmission speed of the bus, either a data reading speeds of the respective drive units or a data writing speeds of the respective drive units) = (m, S and R)'.

Description

technical field [0001] The present invention relates to a data storage system in which a plurality of recording medium drive devices exist on one bus. Background technique [0002] Conventionally, drive devices such as optical disk drives, hard disk drives, and magnetic tape drives have been used for applications such as backing up large amounts of data on recording media. FIG. 1 is a block diagram showing the configuration of a conventional data storage system equipped with a plurality of magnetic tape drives. The data storage system 101 is composed of a data reading control unit 111, a SCSI (Small Computer System Interface) bus 112, and tape drives 121-123 of the same specification. The tape drives 121 to 123 are connected to the data reading control unit 111 via the SCSI bus 112 . The data reading control unit 111 is a personal computer or the like, and includes a CPU 113 , a memory 114 , and a bus interface unit 115 inside. [0003] The data reading control section 11...

AI Technical Summary

Problems solved by technology

[0008] However, in the tape drive, since the tape position needs to be repositioned when the tape is stopped, time is lost in seconds before actually starting to read and write. Therefore, frequent tape stops may cause Problems with reduced data transmission performance or damage to structural components (wear, etc.)

In addition, in the case of using a plurality of disk drives instead of the above-mentioned tape drives 121-123, if the data writing is stopped corresponding to the state of the internal buffer, then (1) there is a head position due to the subsequent start of data writing. The problem of having to spin and wait until the head reaches the next write position on the disk

This problem is more significant when using an optical disk drive with a slow rotation speed than a hard disk drive with a short reading time.

(2) In addition, in disk drives such as CD-R and DVD-R, when writing is started again, it is necessary to leave a gap with the last written data to form a mark, resulting in the inability to follow the previously written data. Problems with writing subsequent data

[0011] However, conventional methods such as calculating the data transfer rate between the data reading control unit 111 and the internal buffer at any time, or dynamically controlling the moving speed of the tape side while constantly monitoring the usage of the internal buffer, or changing the timing of bus reconnection, etc. In the method, it is necessary to add a data transmission rate calculation function, an internal buffer monitoring function, a tape movement speed control function, a dynamic bus reconnection timing change function, etc. to the drive device.

Therefore, the configuration of the tape drive becomes complicated, and the cost of the data storage system becomes high.

[0012] In addition, in the scheme of dynamically controlling the timing of bus reconnection as in the past, because the reconnection control is performed only according to the data transmission speed at that time, the number of drive devices connected to the same bus is not considered, so there are two drives on the same bus. Invalid problem in the presence of multiple drive units

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