Medium controller with medium-identifying information memory

Details Medium controller with medium-identifying information memory Medium controller with medium-identifying information memory

2000-09-26

2003-02-04

Psitos, Aristotelis (Department: 2653)

Dynamic information storage or retrieval

Information location or remote operator actuated control

Selective addressing of storage medium

C369S030270, C707S793000

Reexamination Certificate

active

06515946

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a medium controller for medium-exchange type memory units that is used as peripheral equipment of a computer (for example, an autoloader in a library of magnetic tape units or optical disk units).
The events, such as opening or closing of the entry/exit door, resetting or stopping power supply for the medium controller, are hereafter referred to as medium entry/exit-enable actions. When power supply is stopped or a reset button is pressed, it becomes possible to open or close the door of the medium storage and, after that, a medium may be taken out or put into storage. This is the reason why those events are treated as the medium entry/exit-enable actions. Upon recognizing any of such events, the medium controller has medium storage information with the contents before this event automatically updated or the system site operator issues a command to have the information updated.
Conventionally, when medium storage information is to be updated automatically or by the operator issuing a command, the prior-art medium controller is unable to obtain medium entry/exit information because there is no sensor to recognize a medium in the medium storage area. As a solution, generally, the medium transfer unit (accessor) is equipped with a sensor or a bar-code reader to read a bar code on the medium and the medium transfer unit is made to access all the medium storage places (hereafter referred to as slots) where media are stored, and each time the sensor or the bar-code reader, provided for (accompanying) the accessor, recognizes a medium, the medium storage information is updated. In the prior-art medium transfer unit, each time some medium is replaced manually, the medium transfer unit accesses all medium storage places as mentioned above, taking a long time. Therefore, there is a long waiting time before the medium controller can be accessed from the system.
The conventional medium controller cannot grasp the medium storage status unless the medium transfer unit (accessor) sequentially checks all the slots; therefore, there are the following two problems.
The first problem is that, in a medium controller with a very large number of media in storage, the accessor checks every slot to see what medium is stored. This requires a long time for updating medium storage information. For this reason, in many cases, medium storage information is updated only when the operator desires. Consequently, when a medium is taken out or put into storage especially by manual operation, if the operator does not update medium storage information, it follows that the medium storage information does not match the actual storage status.
The second problem is that, in a medium controller with fewer media in storage, medium storage information is updated automatically in many cases when the condition that media are exchanged occurs, with the result that each time a medium comes in or out, the medium controller is kept waiting while the medium transfer unit is accessing all the slots and cannot perform other processing.
SUMMARY OF THE INVENTION
It is an object of the present invention to greatly reduce time for updating medium storage information when a medium entry/exit-enable action occurs during the backup operation of a computer system, particularly in the operation of the automatic (unmanned) medium controller. This significant time reduction contributes to a substantial solution of the problem of waiting time before the medium controller can be accessed. In addition, because it takes a long time to update the medium storage information in the medium controller with a large number of media in storage, the medium storage information is not necessarily updated each time a medium entry/exit-enable action occurs but the medium information is updated only when the operator thinks it necessary. Therefore, it is another object of the present invention to solve the problem of the discrepancy between medium storage information and the actual storage status. This is accomplished by the above-mentioned significant reduction in time for updating the medium information because this time saving makes it possible to automatically update the medium storage information when a medium entry/exit-enable action occurs.
According to a first aspect of the present invention, there is provided a medium controller storing a plurality of media, having a medium transfer unit to take a medium in and out of a storage place to read or write information on the medium and to transfer the medium to a place where reading and writing information is possible, and managing information about media in storage. This medium controller comprises slots for storing media; sensors, each mounted in each of the slots, for detecting whether or not there is a medium in the slot; a sensor manager for holding a log of status of the sensors in a period when media are likely to be taken in or out manually and deciding changes in the status of the sensors; and a medium information reader for reading medium information, which identifies a medium, from the medium, wherein when it is decided from a decision result by the sensor manager that the medium has been replaced, medium information is read by the medium information reader to thereby update medium storage information, or when it is decided that the medium has not been replaced, the medium storage information is not updated.
According to a second aspect of the present invention, a medium controller further comprises a door open detector for detecting that the door is open at the medium storage place of the medium controller; a door closed detector for detecting that the door is closed; a first memory for storing medium management information showing what media are stored in which slots; and a second memory for storing medium management information showing what media are stored in which slots at the moment when the door close detector detects that the above-mentioned entry/exit door is closed, wherein the medium storage information is updated by writing the medium information, which was read in by the medium information reader, in the first and second memories.
According to a third aspect of the present invention, there is provided a medium controller, wherein the sensor manager comprises a sensor status holder for storing the current sensor status of the respective slots; a log tracer for holding a log of the sensor status of the respective slots when it is found from contents of the sensor status holder that the entry/exit door is opened; and a log trace determiner for checking status changes in sensors from contents of the log tracer, wherein supposing that a sensor status that a medium exists is designated as ON and a sensor status that a medium does not exist is designated as OFF, when a decision result of the sensor status decision unit is OFF→ON or ON→ON, the medium information is read in by the medium information reader and when a decision result is ON→OFF, the medium information is erased and when a decision result is OFF→ON→OFF or that the sensor status remains unchanged, the medium information is not read in by the medium information reader.
According to a fourth aspect of the present invention, there is provided another medium controller storing a plurality of media therein, having a medium transfer unit to take a medium in and out of a storage place to read or write information on the medium and to transfer the medium to a place where reading and writing is possible, and managing information about media in storage. This medium controller comprises slots for storing media; magazines each including a plurality of the slots; sensors, each mounted in each of the magazines, for detecting whether or not a medium has been removed from or stored in a slot; a sensor manager for deciding detection results of sensors in a period when media are likely to be taken out or stored manually; and a medium information reader for reading medium information, which identifies a medium, from the medium, wherein when it is decided from

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