A library controller configured to operate an automated data storage library, said automated data storage library comprising at least a plurality of multi-cartridge deep slot cells, each configured to store up to a plurality of data storage cartridges arranged in sequential order of tiers from front to rear, a plurality of single cartridge storage slots, each configured to store a single data storage cartridge, and a plurality of accessors, each configured to selectively extract, place and transport data storage cartridges with respect to said multi-cartridge deep slot cells and said single cartridge storage slots;
- said library controller comprising:
- at least one computer processor configured in accordance with a computer program product to:
- operate said accessors to selectively extract, place and transport data storage cartridges with respect to said multi-cartridge deep slot cells and said single cartridge storage slots, and with respect to other elements of said automated data storage library;
- and
- in said selectively extracting, placing and transporting operation, if a data storage cartridge is recently used by a selected other element of said automated data storage library, and is to be demounted from said selected other element:
- first, in said selectively extracting, placing and transporting operation, operating a first of said accessors to extract another data storage cartridge from said single cartridge storage slots, vacating one of said single cartridge storage slots, and destage said extracted data storage cartridge to a multi-cartridge deep slot cell;
- and
- second, in said selectively extracting, placing and transporting operation, operating a second of said accessors to extract, transport and place said demounted data storage cartridge in said vacated single cartridge storage slot, thereby swapping said demounted data storage cartridge with said extracted data storage cartridge.