Migration of control in a distributed segmented file system

Abstract

A method of managing segments in a distributed-file system implemented by a plurality of file servers includes determining a segment of the distributed-file system controlled by a first file server for which control is to be migrated, selecting a second file server, that is different from the first file server, to take control of the segment, and moving control of the segment from the first file server to the second file server.

What is claimed is:  
     
         1 . A method of managing segments in a distributed-file system implemented by a plurality of file servers, the method comprising: 
 determining a segment of the distributed-file system controlled by a first file server for which control is to be migrated;    selecting a second file server, that is different from the first file server, to take control of the segment; and    moving control of the segment from the first file server to the second file server.    
     
     
         2 . The method of  claim 1  wherein the moving comprises changing a stored first association of segments and file servers that associates the segment to the first file server to a stored second association that associates of the segment to the second file server.  
     
     
         3 . The method of  claim 2  wherein the changing occurs in each of the plurality of file servers that implement the distributed-file system.  
     
     
         4 . The method of  claim 3  wherein the changing occurs substantially simultaneously in at least each of the file servers whose set of controlled segments is affected by the change.  
     
     
         5 . The method of  claim 4  wherein the changing occurs substantially at a first time in each of the file servers whose set of controlled segments is affected by the change and occurs at a second time, different than the first time, in a file server whose set of controlled segments is unaffected by the change.  
     
     
         6 . The method of  claim 2  wherein the changing comprises modifying a mapping of segments and file servers.  
     
     
         7 . The method of  claim 6  wherein the changing comprises one of editing the mapping of segments and file servers and replacing the mapping of segments and file servers.  
     
     
         8 . The method of  claim 1  further comprising proliferating to each of the file servers at least one indication of the moving of control of the segment.  
     
     
         9 . The method of  claim 8  further comprising proliferating a version number of revised association of segments and file servers.  
     
     
         10 . The method of  claim 9  further comprising verifying a version number, of an association of segments and file servers, associated with an authorization request before providing authorization.  
     
     
         11 . The method of  claim 10  further comprising: 
 denying authorization if the version number associated with the authorization request indicates an older version of the association of segments and file servers than a version of the association of segments and file servers stored in association with a device receiving the authorization request; and  
 obtaining the association of the segments and file servers associated with the version number indicates a newer version of the association of segments and file servers than the version of the association of segments and file servers stored in association with the device receiving the authorization request.  
 
     
     
         12 . The method of  claim 8  further comprising proliferating an indication of a time to effect the moving of control.  
     
     
         13 . The method of  claim 1  wherein moving control of the segment occurs while a memory location that stores the first file server remains unchanged.  
     
     
         14 . The method of  claim 1  further comprising quiescing the segment before moving control of the segment.  
     
     
         15 . The method of  claim 14  further comprising de-quiescing the segment after moving control of the segment.  
     
     
         16 . A device for managing segments in a distributed-file system implemented by a plurality of file servers, the device comprising: 
 a communication interface configured to communicate with the file servers; and    a processor coupled to the communication interface and configured to: 
 determine a segment of the distributed-file system controlled by a first file server for which control is to be migrated;  
 select a second file server, that is different from the first file server, to take control of the segment; and  
 send indicia to the file servers to effect moving of control of the segment from the first file server to the second file server.  
   
     
     
         17 . The device of  claim 16  wherein the indicia are configured to cause the file servers to change a stored first association of segments and file servers that associates the segment to the first file server to a stored second association that associates of the segment to the second file server.  
     
     
         18 . The device of  claim 17  wherein the indicia are configured to cause the change to occur substantially simultaneously in at least each of the file servers whose set of controlled segments is affected by the change.  
     
     
         19 . The device of  claim 18  wherein the indicia are configured to cause the change to occurs substantially at a first time in each of the file servers whose set of controlled segments is affected by the change and occurs at a second time, different than the first time, in a file server whose set of controlled segments is unaffected by the change.  
     
     
         20 . The device of  claim 17  wherein the indicia are configured to cause the file servers to one of edit the first association to become the second association and replace the first association with the second association.  
     
     
         21 . The device of  claim 16  wherein the processor is configured to send further indicia to the file servers to distinguish the second association from the first association.  
     
     
         22 . The device of  claim 21  wherein the further indicia include a version number of second association of segments and file servers.  
     
     
         23 . The device of  claim 16  wherein the processor is configured to send to the file servers an indication of a time to effect the moving of control.  
     
     
         24 . The device of  claim 16  wherein the processor is configured to instruct the first file server to quiesce the segment before control of the segment is moved.  
     
     
         25 . The device of  claim 24  wherein the processor is configured to instruct the second file server to de-quiesce the segment after control of the segment is moved.  
     
     
         26 . A computer program product residing on a computer-readable medium for managing segments in a distributed-file system implemented by a plurality of file servers, the computer program product comprising computer-readable and computer-executable instructions for causing a computer to: 
 determine a segment of the distributed-file system controlled by a first file server for which control is to be migrated;    select a second file server, that is different from the first file server, to take control of the segment; and    send indicia to the file servers to effect moving of control of the segment from the first file server to the second file server.    
     
     
         27 . The computer program product of  claim 26  wherein the indicia are configured to cause the file servers to change a stored first association of segments and file servers that associates the segment to the first file server to a stored second association that associates of the segment to the second file server.  
     
     
         28 . The computer program product of  claim 27  wherein the indicia are configured to cause the change to occur substantially simultaneously in at least each of the file servers whose set of controlled segments is affected by the change.  
     
     
         29 . The computer program product of  claim 28  wherein the indicia are configured to cause the change to occurs substantially at a first time in each of the file servers whose set of controlled segments is affected by the change and occurs at a second time, different than the first time, in a file server whose set of controlled segments is unaffected by the change.  
     
     
         30 . The computer program product of  claim 27  wherein the indicia are configured to cause the file servers to one of edit the first association to become the second association and replace the first association with the second association.  
     
     
         31 . The computer program product of  claim 26  further comprising instructions for causing the computer to send further indicia to the file servers to distinguish the second association from the first association.  
     
     
         32 . The computer program product of  claim 31  wherein the further indicia include a version number of second association of segments and file servers.  
     
     
         33 . The computer program product of  claim 26  further comprising instructions for causing the computer to send to the file servers an indication of a time to effect the moving of control.  
     
     
         34 . The computer program product of  claim 26  further comprising instructions for causing the computer to instruct the first file server to quiesce the segment before control of the segment is moved.  
     
     
         35 . The computer program product of  claim 34  further comprising instructions for causing the computer to instruct the second file server to de-quiesce the segment after control of the segment is moved.