Patent ID: 7937453
Filing Date: 2011-05-03
Classification: G06F

Abstract:
1. In a data processing system including client computers, file servers managing respective file systems, storage arrays storing file data of the file systems, and a namespace server providing the client computers with file access to a virtual file system in accordance with the Network File System (NFS) protocol or the Common Internet File System (CIFS) protocol, the virtual file system containing files of the respective file systems managed by the file servers, a method of providing at least one of the client computers with read or write access to a specified file in the virtual file system, said method comprising: said at least one of the client computers sending to the namespace server a first metadata access request in accordance with a file mapping protocol for metadata access to the specified file, and the namespace server responding to the first metadata request by determining that the specified file is not presently being migrated, and upon determining that the specified file is not presently being migrated, the namespace server returning to said at least one of the client computers a redirection reply redirecting said at least one of the client computers to one of the file servers managing a respective one of the file systems including the specified file, and said at least one of the client computers receiving the redirection reply and using the redirection reply to obtain file mapping metadata from said one of the file servers managing the respective one of the file systems including the specified file, and using the file mapping metadata to produce a block access request sent to one of the storage arrays storing file data of the specified file to read data from or write data to the specified file; and said at least one of the client computers sending a second metadata access request in accordance with the file mapping protocol to the namespace server for metadata access to the specified file, and the namespace server responding to the second metadata request by determining that the specified file is now being migrated, and upon determining that the specified file is now being migrated, the namespace server returning to said at least one of the client computers a metadata access denied reply, and said at least one of the client computers receiving the metadata access denied reply and responding to the metadata access denied reply by sending to the namespace server a read or write request in accordance with the Network File System (NFS) protocol or the Common Internet File System (CIFS) protocol to read data from or write data to the specified file as requested by said at least one client computer.