Apparatus and method to provide failover protection to a data storage and retrieval system

An accessor moveably disposed in a data storage and retrieval system, wherein said data storage and retrieval system includes one or a plurality of portable data storage media, comprising:

• an accessor controller;
• a work queue stored in said accessor controller;
• an inventory stored in said accessor controller;
• a lifting servo section comprising;
• a centering cam;
• a centering plunger, wherein said centering plunger has a first end and a second end, and wherein said first end extends outwardly from said lifting servo section and said second end is disposed adjacent said centering cam;
• a gripper mechanism frame disposed on said centering cam;
• and
• a gripper mechanism disposed on said gripper mechanism frame.

A data storage and retrieval system, comprising:

• one or a plurality of portable data storage media;
• two or more accessors moveably disposed therein;
• a data and control network;
• wherein each of said two or more accessors communicate with one another using said data and control network, and wherein each of said two or more accessors comprises:
• an accessor controller;
• a work queue stored in said accessor controller;
• an inventory stored in said accessor controller, wherein said inventory comprises the identity of each of said one or a plurality of portable data storage media;
• wherein said accessor controller creates and maintains said inventory and said work queue.

A method to perform a work request provided to a data storage and retrieval system, wherein said data storage and retrieval system includes two or more moveable accessors in communication with one another and two or more accessor controllers, wherein each accessor comprises an accessor controller and a work queue stored in that accessor controller, and wherein said two or more accessors include a first accessor and one or more remaining accessors, said method comprising the steps of:

• providing a work request to each of said two or more accessors;
• creating by each of said two or more accessor controllers a pending work entry comprising said work request;
• adding said pending work entry to the work queue stored in each of said two or more accessor controllers;
• communicating a notification from said first accessor to said remaining accessors that said first accessor is initiating said pending work entry;
• acknowledging said notification by said one or more remaining accessors;
• reporting by said first accessor to said one or more remaining accessors the status of said pending work entry;
• and
• updating the work queue disposed in each of said two or more accessors to include the status of said pending work entry.

A method to provide failover protection in a data storage and retrieval system in the event of an accessor failure, wherein said data storage and retrieval system includes a garage, one or more portable data storage media, two or more moveable accessors, and two or more accessor controllers, wherein said two or more accessors can communicate with one another, and wherein each of said two or more accessors comprises an accessor controller and a work queue stored in that accessor controller, and wherein said two or more accessors include a first accessor and one or more remaining accessors, said method comprising the steps of:

• providing a work request to each of said two or more accessors;
• creating by each of said two or more accessor controllers a pending work entry comprising said work request;
• adding said pending work entry to the work queue stored in each of said two or more accessor controllers;
• communicating a notification from said first accessor to said one or more remaining accessors that said first accessor is initiating said pending work entry;
• acknowledging said notification by each of said remaining accessors;
• determining if said first accessor reports completion of said pending work entry;
• and
• determining if said first accessor can communicate with said one or more remaining accessors.

A method to add a portable data storage medium to a data storage and retrieval system, wherein said data storage and retrieval system comprises an accessor, an import/export station, and a plurality of storage slots, wherein said accessor comprises an accessor controller comprising an inventory of portable data storage media stored in said data storage and retrieval system, said method comprising the steps of:

• disposing a designated portable data storage medium in said import/export station;
• retrieving said designated portable data storage medium;
• determining identification information for said designated portable data storage medium;
• assigning by said accessor controller a storage location, wherein said storage location comprises one of said plurality of storage slots;
• and
• adding by said accessor controller said identification information and said storage location to said inventory.

A data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein to provide failover protection in a data storage and retrieval system, wherein said data storage and retrieval system includes a garage, one or a plurality of portable data storage media, two or more moveable accessors, two or more accessor controllers, wherein said two or more accessors can communicate with one another, wherein each of said two or more accessors comprises an accessor controller and a work queue stored in that accessor controller, and wherein said two or more accessors include a first accessor and one or more remaining accessors, the computer readable program code comprising a series of computer readable program steps to effect:

• providing a work request to each of said two or more accessors;
• creating by each of said two or more accessor controllers a pending work entry comprising said work request;
• adding said pending work entry to the work queue stored in each of said two or more accessor controllers;
• communicating a notification from said first accessor to said one or more remaining accessors that said first accessor is initiating said pending work entry;
• acknowledging said notification by each of said remaining accessors;
• determining if said first accessor reports completion of said pending work entry;
• and
• determining if said first accessor can communicate with said one or more remaining accessors.

A data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein to add a designated portable data storage medium to a data storage and retrieval system, wherein said data storage and retrieval system comprises an accessor, an import/export station, and a plurality of storage slots, wherein said accessor comprises an accessor controller and an inventory of portable data storage media disposed in said data storage and retrieval system, the computer readable program code comprising a series of computer readable program steps to effect:

• retrieving a designated portable data storage medium disposed in said import/export station;
• determining identification information for said designated portable data storage medium;
• assigning a storage location, wherein said storage location comprises one of said plurality of storage slots;
• and
• adding said storage location to said inventory.

A method to remove a data storage medium from a data storage and retrieval system, wherein said data storage and retrieval system comprises a plurality of storage cells, an import/export station, two or more moveable accessors in communication with one another, and two or more accessor controllers, wherein each accessor comprises an accessor controller, a work queue stored in that accessor controller and an inventory stored in that accessor controller, and wherein said two or more accessors include a first accessor and one or more remaining accessors, said method comprising the steps of:

• providing a work request to each of said two or more accessors, wherein said work request comprises removing a designated data storage medium from said data storage and retrieval system;
• creating by each of said two or more accessor controllers a pending work entry comprising said work request;
• adding said pending work entry to the work queue stored in each of said two or more accessor controllers;
• retrieving by said first accessor said designated data storage medium;
• transporting said designated data storage medium to said import/export station;
• disposing said new data storage medium in said import/export station;
• removing said designated data storage medium from said inventory disposed in each of said two or more accessors;
• and
• updating the work queue disposed in each of said two or more accessors to completion of said pending work entry.

A data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein to remove a portable data storage media from a data storage and retrieval system, wherein said data storage and retrieval system comprises a plurality of storage cells, an import/export station, two or more moveable accessors in communication with one another, and two or more accessor controllers, wherein each accessor comprises an accessor controller, a work queue stored in that accessor controller and an inventory stored in that accessor controller, and wherein said two or more accessors include a first accessor and one or more remaining accessors, the computer readable program code comprising a series of computer readable program steps to effect:

• providing a work request to each of said two or more accessors, wherein said work request comprises removing a designated data storage medium from said data storage and retrieval system;
• creating by each of said two or more accessor controllers a pending work entry comprising said work request;
• adding said pending work entry to the work queue stored in each of said two or more accessor controllers;
• retrieving by said first accessor said designated data storage medium;
• transporting said designated data storage medium to said import/export station;
• disposing said new data storage medium in said import/export station;
• removing said designated data storage medium from said inventory disposed in each of said two or more accessors;
• and
• updating the work queue disposed in each of said two or more accessors to completion of said pending work entry.

A method to return a first accessor to service in a data storage and retrieval system, wherein said data storage and retrieval system comprises a garage, two or more moveable accessors in communication with one another, and two or more accessor controllers, wherein each accessor comprises an accessor controller, a work queue stored in that accessor controller, and an inventory stored in that accessor controller, and wherein said two or more accessors include a first accessor and one or more remaining accessors, and wherein said first accessor is moveably disposed in said garage, said method comprising the steps of:

• erasing the work queue disposed in said first accessor;
• erasing the inventory disposed in said first accessor;
• copying by the accessor controller disposed in said first accessor the work queue disposed in one of said remaining accessors;
• copying by the accessor controller disposed in said first accessor the inventory disposed in one of said remaining accessors;
• and
• signaling said remaining accessors by said first accessor that said first accessor is operational.

A data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein to return a first accessor to service, wherein said data storage and retrieval system comprises a garage, two or more moveable accessors in communication with one another, and two or more accessor controllers, wherein each accessor comprises an accessor controller, a work queue stored in that accessor controller and an inventory stored in that accessor controller, and wherein said two or more accessors include a first accessor and one or more remaining accessors, and wherein said first accessor is moveably disposed in said garage, the computer readable program code comprising a series of computer readable program steps to effect:

• erasing the work queue disposed in said first accessor;
• erasing the inventory disposed in said first accessor;
• copying by the accessor controller disposed in said first accessor the work queue disposed in one of said remaining accessors;
• copying by the accessor controller disposed in said first accessor the inventory disposed in one of said remaining accessors;
• and
• signaling said remaining accessors by said first accessor that said first accessor is operational.