Data storage system with redundant media handling assemblies

Abstract

A data storage system comprising: a media picker displacement path having a first end and a second end; a first media picker assembly mounted in the picker displacement path; a second media picker assembly mounted in the picker displacement path; a plurality of data storage media access locations located along the picker displacement path; the first media picker assembly being displaceable along the path from the first end to a point of interfering contact with the second media picker assembly; the second media picker assembly being displaceable along the path from the second end to a point of interfering contact with the first media picker assembly; the storage system having a normal running operating mode wherein the first media picker assembly is stationarily positioned at the first end of the displacement path and the second picker assembly is selectively positionable along the remainder of the path; the storage system having a fall back running operating mode wherein the second media picker assembly is stationarily positioned at the second end of the displacement path and the first picker assembly is selectively positionable along the remainder of the path.

We claim:  
     
         1 . A data storage system comprising: 
 a) a housing assembly having a first end and a second end and having an open shaft extending between said first end and said second end and comprising: 
 i) a first housing unit having a first portion of said open shaft extending therethrough, said first unit being positioned proximate said first end of said housing assembly;  
 ii) a second housing unit having a second portion of said open shaft extending therethrough, said second unit being positioned proximate said second end of said housing assembly; 
 iii) at least a third housing unit having a third portion of said open shaft extending therethrough having a plurality of data media receiving devices mounted therein, said third housing unit being disposed between said first and second housing units;  
 
   b) a first media handling assembly displaceably positioned within said open shaft; and    c) a second media handling assembly displaceably positioned within said open shaft.    
     
     
         2 . The data storage system of  claim 1 , said data storage system having a first operating mode wherein said first media handling assembly is stationarily positioned within said first portion of said shaft and said second media handling assembly is positioned in said shaft in other than said first portion.  
     
     
         3 . The data storage system of  claim 2 , said data storage system having a second operating mode wherein said second media handling assembly is stationarily positioned within said second portion of said shaft and said first media handling assembly is positioned in said shaft in other than said second portion.  
     
     
         4 . The data storage system of  claim 3  wherein, in said first operating mode, said second media handling assembly is positioned in said shaft in other than said first portion and said second portion and wherein, in said second operating mode, said second media handling assembly is positioned in said shaft in other than said first portion and said second portion.  
     
     
         5 . The data storage system of  claim 1 , said data storage system having a pre-startup mode wherein said second media handling assembly is positioned in said second portion of said shaft and said first media handling assembly is positioned in said shaft next adjacent to said second media handling assembly.  
     
     
         6 . The data storage system of  claim 4 , said data storage system having a pre-startup mode wherein said second media handling assembly is positioned in said second portion of said shaft and said first media handling assembly is positioned in said shaft next adjacent to said second media handling assembly.  
     
     
         7 . The data storage system of  claim 6  comprising a plurality of housing units disposed between said first and second housing units and having portions of said open shaft extending therethrough and having a plurality of data media receiving devices mounted therein.  
     
     
         8 . A data storage system comprising: 
 a) a media picker displacement path having a first end and a second end;    b) a first media picker assembly mounted in said picker displacement path;    c) a second media picker assembly mounted in said picker displacement path;    d) a plurality of data storage media access locations located along said picker displacement path;    e) said first media picker assembly being displaceable along said path from said first end to a point of interfering contact with said second media picker assembly;    f) said second media picker assembly being displaceable along said path from said second end to a point of interfering contact with said first media picker assembly.    
     
     
         9 . The data storage system of  claim 8 , said storage system having a pre-startup operating mode wherein said first media picker assembly is positioned at said first end of said displacement path and said second picker assembly is positioned next adjacent said first picker assembly.  
     
     
         10 . The data storage system of  claim 8 , said storage system having a normal running operating mode wherein said first media picker assembly is stationarily positioned at said first end of said displacement path and said second picker assembly is selectively positionable along the remainder of said path.  
     
     
         11 . The data storage system of  claim 10 , said storage system having a fall back running operating mode wherein said second media picker assembly is stationarily positioned at said second end of said displacement path and said first picker assembly is selectively positionable along the remainder of said path.  
     
     
         12 . The data storage system of  claim 11 , said storage system having a transition mode of operation occurring between said normal running mode and said fall back mode wherein said second picker assembly moves from an intermediate position in said path to said second end of said path.  
     
     
         13 . A method of operating a data storage library comprising: 
 moving data storage media between media holding positions located along a one-picker-at-a-time picker displacement path with a second media picker assembly until the second media picker assembly malfunctions;    after it malfunctions moving the second picker assembly a to a second end of the picker displacement path;    maintaining a first media picker assembly at a stationary position at a first end of the picker displacement path until the second picker assembly malfunctions;    after the second picker assembly malfunctions moving data storage media between media holding positions located along the picker displacement path with the first picker assembly.    
     
     
         14 . The method of  claim 16  wherein moving the second picker assembly to a second end of the picker displacement path comprises moving the second picker assembly with the force of gravity.  
     
     
         15 . The method of  claim 16  wherein moving the second picker assembly to a second end of the picker displacement path comprises moving the second picker assembly with an auxiliary drive unit mounted on the second picker assembly.  
     
     
         16 . The method of  claim 16  wherein moving the second picker assembly to a second end of the picker displacement path comprises moving the second picker assembly with the first picker assembly.