Network file server using a cached disk array storing a network file directory including file locking information and data mover computers each having file system software for shared read-write file access

A file server for serving clients in a data network, the file server comprising:

• a cached disk storage subsystem including a semiconductor cache memory, an array of disk drives, a plurality of channel directors for interfacing the semiconductor cache memory to the data mover computers, and a plurality of disk directors and disk adapters for interfacing the semiconductor cache memory to the array of disk drives;
• and
• a plurality of data mover computers connected to the cached disk storage subsystem and linked to the data network for responding to a request for file access from a client in the data network by transferring data between the cached disk storage subsystem and the data network;
• wherein the cached disk storage subsystem stores read-write files which are shared among the clients and each read-write file is accessible by the clients through more than one of the data mover computers, and the data mover computers maintain in the cached disk storage subsystem a file directory accessible by the data mover computers in response to file access requests to determine whether or not file access for a client is permitted, to map file names to logical blocks of data that comprise the files and said logical blocks of data are stored in the cached disk storage subsystem, and to lock and unlock each of the read-write files for shared read-write access among the clients through more than one of the data mover computers, wherein each data mover computer is programmed to access the locking information in the cache memory of the cached disk storage subsystem in order to obtain a read lock or a write lock on at least a portion of each of the read-write files to be accessed;
• wherein file system software for managing the file directory is replicated in each data mover computer, the file system software including software for managing mapping of names of files accessible by the clients to the logical blocks of data that comprise the files and said logical blocks of data are stored in the cached disk storage subsystem, and software for accessing the file directory to determine whether or not a read-write file to be accessed is locked, and when a read-write file to be accessed is not locked, to update the file directory by placing a lock on at least a portion of the read-write file to be accessed, and
• wherein the cached disk storage subsystem responds to requests from the data mover computers for access to logical block addresses of the logical blocks comprising the files to be accessed by the clients, and the cached disk storage subsystem has a limited internal locking facility for ensuring that reading and writing to a logical block is an atomic operation.

A file server for serving clients in a data network, the file server comprising:

• a cached disk storage subsystem including a semiconductor cache memory, an array of disk drives, a plurality of channel directors for interfacing the semiconductor cache memory to the data mover computers, and a plurality of disk directors and disk adapters for interfacing the semiconductor cache memory to the array of disk drives;
• and
• a plurality of data mover computers connected to the cached disk storage subsystem and linked to the data network for responding to a request for file access from a client in the data network by transferring data between the cached disk storage subsystem and the data network;
• wherein the cached disk storage subsystem stores read-write files which are shared among the clients and each read-write file is accessible by the clients through more than one of the data mover computers, and the data mover computers maintain in the cached disk storage subsystem a file directory accessible by the data mover computers in response to file access requests to determine whether or not file access for a client is permitted, to map file names to logical blocks of data that comprise the files and said logical blocks of data are stored in the cached disk storage subsystem, and to lock and unlock each of the read-write files for shared read-write access among the clients through more than one of the data mover computers, wherein each data mover computer is programmed to access the locking information in the cache memory of the cached disk storage subsystem in order to obtain a read lock or a write lock on at least a portion of each of the read-write files to be accessed;
• wherein each of the data mover computers is a commodity personal computer, the data movers are linked together by a data link internal to the file server, and each of the data mover computers includes a real-time scheduler for scheduling real-time tasks and general purpose tasks;
• wherein file system software for managing the file directory is replicated in each data mover computer, the file system software including software for managing mapping of names of files accessible by the clients to the logical blocks of data that comprise the files and said logical blocks of data are stored in the cached disk storage subsystem, and software for accessing the file directory to determine whether or not a read-write file to be accessed is locked, and when a read-write file to be accessed is not locked, to update the file directory by placing a lock on at least a portion of the read-write file to be accessed, and wherein the file server supports at least one industry standard network file access protocol, and the file server has multiple file systems existing concurrently over multiple communication stacks, with shared data access;
• and
• wherein the cached disk storage subsystem responds to requests from the data mover computers for access to the logical block addresses of the logical blocks that comprise the files to be accessed by the clients, and the cached disk storage subsystem has a limited internal locking facility for ensuring that reading and writing to a logical block is an atomic operation.

A method of operating a file server for serving clients in a data network, the file server including a cached disk storage subsystem and a plurality of data mover computers linking the cached disk storage subsystem to the data network for transfer of data between the cached disk storage subsystem and the data network, and the cached disk storage subsystem having an array of disk drives and a semiconductor cache memory for storing data written to and read from the array of disk drives, said method comprising the steps of:

• (a) maintaining in the cached disk storage subsystem a file directory accessible by the data mover computers in response to file access requests to determine whether or not file access by a client is permitted, and to map file names to logical blocks of data storage that comprise the files and said logical blocks of data are stored in the cached disk storage subsystem, the file directory including locking information for read-write files which are shared among the clients, wherein the read-write files are accessible by the clients through more than one of the data mover computers;
• and
• (b) one of the data mover computers receiving from one of the clients a request for read/write file access to a shared read/write file, said one of the data mover computers accessing the file directory to determine whether or not file access by said one of the clients is permitted, and when read/write file access by said one of the clients is permitted, said one of the data mover computers accessing the locking information in the semiconductor cache memory of the cached disk storage subsystem in order to obtain a read lock or a write lock on a portion of the shared read-write file, and satisfying the request by transferring data between the cached disk storage subsystem and the data network.

A method of operating a file server for serving clients in a data network, the file server including a cached disk storage subsystem and a plurality of data mover computers linking the cached disk storage subsystem to the data network for transfer of data between the cached disk storage subsystem and the data network, and the cached disk storage subsystem having an array of disk drives and a semiconductor cache memory for storing data written to and read from the array of disk drives, said method comprising the steps of:

• (a) maintaining in the cached disk storage subsystem a file directory accessible by the data mover computers in response to file access requests to determine whether or not file access by a client is permitted, and to map file names to logical blocks of data said logical blocks of data comprise the files and that are stored in the cached disk storage subsystem, the file directory including locking information for read-write files which are shared among the clients, wherein the read-write files are accessible by the clients through more than one of the data mover computers;
• and
• (b) one of the data mover computers receiving from one of the clients a request for read/write file access to a shared read/write file, said one of the data mover computers accessing the file directory to determine whether or not file access by said one of the clients is permitted, and when read/write file access by said one of the clients is permitted, said one of the data mover computers accessing the locking information in the semiconductor cache memory of the cached disk storage subsystem in order to obtain a read lock or a write lock on at least a portion of the shared read-write file, and satisfying the request by transferring data between the cached disk storage subsystem and the data network;
• wherein said one of the data mover computers maintains the file directory by managing mapping of names of files accessible by the clients to logical blocks of data that comprise the files and said logical blocks of data are stored in the integrated cached disk array storage subsystem, and wherein the cached disk storage subsystem responds to requests from the data mover computers for access to logical block addresses of the logical blocks that comprise the files to be accessed by the clients, and ensures that reading and writing to a logical block is an atomic operation.