Fault-tolerant computer network file systems and methods

Abstract

A system and method for replacing file system processors, also known as hot swapping, is described. The system and method operate on a fault-tolerant network file system that includes a first file server that is operably connected to a network fabric and a second file server that is operably connected to the network fabric. The fault-tolerant network file system includes a first disk array that is operably coupled to the first file server and to the second file server and a second disk array that is operably coupled to the first file server and to the second file server. First file system information is loaded on the first file server. The first file system information includes a first intent log of proposed changes to first metadata. Second file system information is loaded on the second file server. The second file system information includes a second intent log of proposed changes to second metadata. The first file server has a copy of the second metadata, and the second file server maintains a copy of the first metadata, thereby allowing the first file server to access files on the second disk array in the event of a failure of the second file server.

1 . A computer network file system, comprising: 
 a first file server operably connected to a network fabric and to a first disk array and to a second disk array;    a second file server operably connected to said network fabric and to said first disk array and to said second disk array;    means for locating files stored by said first file server and files stored by said second file server by traversing a directory structure that spans. at least said first file server and said second file server; and    means for allowing said first file server to complete file system changes intended by said second file server but not completed due to said second file server going offline.    
   
   
       2 . The computer network file system of  claim 1 , wherein said directory structure comprises location information for a first file, said location information comprising a server id that identifies at least said first file server or said second file server.  
   
   
       3 . The computer network file system of  claim 1 , wherein said directory structure comprises server ids of servers that contain sub-directories.  
   
   
       4 . The computer network file system of  claim 1 , further comprising means for sharing workload between said first file server and said second file server.  
   
   
       5 . The computer network file system of  claim 1 , further comprising means for detecting that said second file server has come online and handing at least a portion of file system operations dealing with said second disk array over to said second file server.  
   
   
       6 . The computer network file system of  claim 1 , wherein said network fabric comprises a Fibre channel network.  
   
   
       7 . The computer network file system of  claim 1 , wherein said network fabric comprises an ethernet network.  
   
   
       8 . A method for hot-swapping file servers in a computer network, the method comprising: 
 connecting a first file server to a network fabric and to a first disk array and to a second disk array;    connecting a second file server to said network fabric and to said first disk array and to said second disk array;    locating files stored by said first file server and files stored by said second file server by traversing a directory structure that spans at least said first file server and said second file server; and    completing, with said first file server file system, changes intended by said second file server but not completed due to said second file server going offline.    
   
   
       9 . The method of  claim 8 , wherein said directory structure comprises location information for a first file, said location information comprising a server id that identifies at least said first file server or said second file server.  
   
   
       10 . The method of  claim 8 , wherein said directory structure comprises server ids of servers that contain sub-directories.  
   
   
       11 . The method of  claim 8 , additionally comprising sharing a workload between said first file server and said second file server.  
   
   
       12 . The method of  claim 8 , additionally comprising detecting that said second file server has come online and handing at least a portion of file system operations dealing with said second disk array over to said second file server.  
   
   
       13 . The method of  claim 8 , wherein said network fabric comprises a Fibre channel network.  
   
   
       14 . The method of  claim 8 , further comprising detecting with said first file server when said second file server goes offline.  
   
   
       15 . A fault-tolerant computer network file system, comprising: 
 a first file server operably connected to a network fabric and to a first disk array and to a second disk array;    a second file server operably connected to said network fabric and to said first disk array and to said second disk array; and    metadata comprising information indicative of locations of files stored by said first file server and files stored by said second file server, said metadata further comprising directory information describing a directory structure that spans at least said first file server and said second file server,    wherein said first file server is capable of completing file system changes intended by said second file server but not completed due to said second file server going offline.    
   
   
       16 . The fault-tolerant computer network file system of  claim 15 , wherein said directory structure comprises location information for a first file, said location information comprising a server id that identifies at least said first file server or said second file server.  
   
   
       17 . The fault-tolerant computer network file system of  claim 15 , wherein said directory structure comprises server ids of servers that contain sub-directories.  
   
   
       18 . The fault-tolerant computer network file system of  claim 15 , further comprising means for sharing workload between said first file server and said second file server.  
   
   
       19 . The fault-tolerant computer network file system of  claim 15 , further comprising means for detecting that said second file server has come online and handing at least a portion of file system operations dealing with said second disk array over to said second file server.  
   
   
       20 . The fault-tolerant computer network file system of  claim 15 , wherein said network fabric comprises a Fibre channel network.