Concurrent read and write access to simulated sequential data of a removable random access data storage medium

An automated data storage library for storing and retrieving tape media and removable random access data storage media, at least one of said removable random access data storage media storing data comprising a plurality of data segments, at least some of said data segments comprising at least one partition;

• said library comprising:
• a plurality of storage shelves for storing said tape media and for storing said removable random access data storage media;
• at least one data storage drive for providing concurrent read and write access by at least one host to data stored on said at least one removable random access data storage medium storing data comprising a plurality of data segments;
• at least one robot for storing and retrieving said tape media and for storing and retrieving said removable random access data storage media at said storage shelves, and for loading and removing said removable random access data storage media to and from said data storage drive;
• a library control coupled to said robot and to said data storage drive, for operating said robot to store and retrieve said tape media at said storage shelves, to store and retrieve said removable random access data storage media at said storage shelves, and to load and remove said removable random access data storage media to and from said data storage drive;
• a plurality of logical accessors associated with said data storage drive, each said logical accessor arranged to communicate with said at least one host for read and/or write access to said removable random access data storage medium;
• a read/write access unit providing read and write access at said data storage drive to said removable random access data storage medium;
• and
• a read/write control for said data storage drive coupled to said plurality of logical accessors and to said read/write access unit, said read/write control:
• responds to said read and/or write access of one of said logical accessors to one of said partitions of one of said removable random access data storage media storing data comprising a plurality of data segments loaded at said data storage drive, identifying at least one said data segment as comprising said partition for said access;
• upon occurrence of a write access for at least a data segment of said identified partition by one of said logical accessors, establishes, as a write accessed context, at least said one data segment of said identified partition for said write access, locking said write accessed context to said one of said logical accessors;
• operates said read/write access unit to access said write accessed context for said locked write access one of said logical accessors;
• concurrently operates said read/write access unit to provide read and/or write access to said data of said removable random access data storage medium by other said logical accessors than said locked write access one of said logical accessors;
• preventing read access to said write accessed context by any logical accessor other than said locked write access one of said logical accessors;
• and preventing write access to any data of said locked write access partition of said removable random access data storage medium by other than said locked write access one of said logical accessors;
• and
• upon completion of said write access by said locked write access one of said logical accessors, releases said locking of said write accessed context to said locked write access one of said logical accessors.

A method for providing concurrent read and write access by at least one host to data storable on a removable random access data storage medium;

• said data comprising a plurality of data segments, at least some of said data segments comprising at least one partition;
• said removable random access data storage medium accessible at and removable from a data storage drive;
• said method comprising the steps of:
• arranging said data storage drive as a plurality of logical accessors, each said logical accessor arranged to communicate with said at least one host for read and/of write access to said removable random access data storage medium;
• in response to a read and/or write access of one of said logical accessors to one of said partitions, identifying at least one said data segment as comprising said partition for said access;
• upon occurrence of a write access for at least a data segment of said identified partition by one of said logical accessors, establishing, as a write accessed context, at least said one data segment of said identified partition for said write access, locking said write accessed context to said one of said logical accessors;
• accessing said write accessed context for said locked write access one of said logical accessors;
• concurrently allowing read and/or write access to said data of said removable random access data storage medium by other said logical accessors than said locked write access one of said logical accessors;
• preventing read access to said write accessed context by any logical accessors other than said locked write access one of said logical accessors;
• and preventing write access to any data of said locked write access partition of said removable random access data storage medium by other than said locked write access one of said logical accessors;
• and
• upon completion of said write access by said locked write access one of said logical accessors, releasing said locking of said write accessed context to said locked write access one of said logical accessors.