Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
1999-01-11
2001-09-04
Peikari, B. James (Department: 2186)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S111000, C711S114000, C711S161000
Reexamination Certificate
active
06286079
ABSTRACT:
TECHNICAL FIELD
This invention relates to mass data storage libraries for storing data storage media in storage shelves, and, more particularly, to conducting an inventory of the media stored in the storage shelves.
BACKGROUND OF THE INVENTION
A mass data storage library typically stores thousands of data storage media. When the library is powered up, an inventory must be conducted to determine the specific data storage media, if any, stored in each storage shelf.
Typically, the inventory is conducted by a robot in the library. The robot normally is used to transport data storage media between the storage shelves and data storage drives for reading and/or writing data on the media. Hence, instead of transporting media, a scanner, viewer or other sensor mounted on the robot is moved to each individual storage shelf, and is operated to read an identifier on the data storage media stored in the storage shelf, or to detect that the storage shelf is empty. U.S. Pat. No. 5,059,772, Younglove, illustrates an example of an automated magnetic tape cartridge library and a method for taking a library inventory, necessitated by possible manual removal or insertion of cartridges after opening of a library door.
Additionally, a mass data storage library is often employed to store data for a plurality of host computer systems. As the result, each host needs to have an inventory of the storage shelves storing data storage media assigned, either on a sole or on a shared basis, to the host. For example, U.S. Pat. No. 5,416,914, Korngiebel et al., illustrates a single mass data storage library for storing a plurality of types of media, and having a corresponding plurality of types of data storage drives for reading and/or writing on the media. The library is partitioned into corresponding subsets which have consistent mechanical and electrical characteristics, and a management system maps the media type as part of the inventory.
Thus, when the library is powered up, the library must conduct an inventory, and then each host, upon sensing that the library is powered up, will also request an inventory. In prior libraries, each inventory is then separately conducted.
During each of these inventory processes, the library is prevented from transporting any media for two reasons. First, the robot is conducting the inventory and is unavailable, and, second, any movement of a media to or from one storage shelf, or from one storage shelf to another, will corrupt any inventory.
After the inventory is completed, an inventory manager of the library will typically track all movements of the robot and thereby track any changes in position of the media. Thus, the inventory is continually updated.
However, mass data storage libraries often are provided with doors or other access to the storage shelves and/or to the robot. This will allow an operator to repair or modify the robot, or to add or remove media from the storage shelves. Hence, when an access door is opened, the potential exists to modify the content of the library, and the inventory must be again be taken. Therefore, the library is once again removed from service, and the robot operated to take an inventory. Additionally, the hosts may be informed of the access door opening and each will command that an inventory be taken, again prolonging the library's removal from service in order to repeat the inventory.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an inventory of a mass data storage library while not requiring removal of the library from service during the inventory.
Another object of the present invention is to prevent repetitions of the same inventory to satisfy request for an inventory while another inventory is being conducted.
Disclosed are a method, a computer program product and a system for conducting an inventory of data storage media stored in a mass data storage library. The library storage shelves are organized into a plurality of subsets of storage shelves for the purpose of conducting the inventory. In response to an inventory command, the inventory of the media stored in the subsets of storage shelves is conducted in a predetermined order by subset. Upon completion of the inventory of each subset of storage shelves, the completion is posted in a list. A command input detects newly issued commands (subsequent to the inventory command), places them in a queue, and upon detecting a command for a non-inventory process (such as a media move), the inventory of the subsets of storage shelves is interrupted, stopping the inventory of the subsets of storage shelves. If no subset of storage shelves for which a completion has been posted is involved in the non-inventory process, the non-inventory process is conducted, and, upon completion of the non-inventory process, the inventory is resumed.
In another aspect of the present invention, upon detecting a newly issued inventory command subsequent to the initiation of the inventory step and prior to completion of the inventory, the subsequent inventory command is incorporated into the inventory step.
In response to an occurrence of an event which may corrupt the inventory, the posting of some or all the subsets of storage shelves are reset to incomplete.
In an additional aspect of the present invention, where the non-inventory move process comprises moving one of the media from a source to a destination, and if the source comprises a storage shelf from a recently inventoried subset for which a completion has been posted, the non-inventory move step is additionally conducted, and the inventory of the subset of storage shelves for which a completion has been posted is updated upon completion of the move.
For a fuller understanding of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.
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Basham Robert Beverley
Greco Paul Merrill
Jesionowski Leonard George
Chace Christian P.
Holcombe John H.
International Business Machines - Corporation
Peikari B. James
Sullivan Robert M.
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