Abstract: A distributed network storage system provides capability to send and receive storage information from multiple network storage servers in a storage area network using iSCSI commands. A storage server system comprising at least two data storage servers stores one or more logical volumes of data. A host computer receives a storage command from a host application, and determines one or more data storage servers has information to complete the storage command. The host computer generates one or more iSCSI network commands to carry out the storage command, and transmits the iSCSI network commands directly to each data storage server having necessary information. The storage servers receive iSCSI network commands, and return a response to the host. The host and storage servers verify the configuration of the storage network and are capable of correcting or updating the configuration as required.

Abstract: In a client/server computing system, a method and apparatus for efficiently storing entries in a log file during disconnected client operations. An encoder utilizes a log file and a write file table for logging the write operations performed by the client during disconnected operations. The logging method employed by the encoding module logs in the log file only writes associated for different files. The encoding module tracks the status of the entries in the log file with a write file table containing the most recent sequence number associated with a file entry of the log file. Upon reconnection of the client to the server, a decoding module replays the events in the correct chronological order by transferring the file data modified during the period of disconnection in the order dictated by the write file table. A deferred write list is accessed by the decoding module for temporary storage any write operations whose replay should be delayed to preserve the relative order of events.

Abstract: In a client/server computing environment where the server controls the creation and allocation of file numbers for newly created files, transparent creation by the client of new file numbers while the server is unavailable. A file number table is created and maintained in the client for storing and mapping file numbers. Responsive to requests for the creation of a new file while the server is unavailable, the client creates a new file number for the new file, stores it in the table, and maps it to the file number later assigned by the server. Conflicts between file numbers created by the server and client are also flagged, detected, and resolved.

Abstract: In a client/server computing system, a method and apparatus for efficiently storing entries in a log file during disconnected client operations. An encoder utilizes a log file and a write file table for logging the write operations performed by the client during disconnected operations. The logging method employed by the encoding module logs in the log file only writes associated for different files. The encoding module tracks the status of the entries in the log file with a write file table containing the most recent sequence number associated with a file entry of the log file. Upon reconnection of the client to the server, a decoding module replays the events in the correct chronological order by transferring the file data modified during the period of disconnection in the order dictated by the write file table. A deferred write list is accessed by the decoding module for temporary storage any write operations whose replay should be delayed to preserve the relative order of events.

Abstract: In a client/server computing system, a method and apparatus for efficiently storing entries in a log file during disconnected client operations. An encoder utilizes a log file and a write file table for logging the write operations performed by the client during disconnected operations. The logging method employed by the encoding module logs in the log file only writes associated for different files. The encoding module tracks the status of the entries in the log file with a write file table containing the most recent sequence number associated with a file entry of the log file. Upon reconnection of the client to the server, a decoding module replays the events in the correct chronological order by transferring the file data modified during the period of disconnection in the order dictated by the write file table. A deferred write list is accessed by the decoding module for temporary storage any write operations whose replay should be delayed to preserve the relative order of events.

Abstract: A digital data storage apparatus has primary, secondary and backing storage elements characterized by respectively longer access times. A level detector signals when the quantity of data in the secondary store exceeds a threshold amount. A data migrator responds by moving selected data files from the secondary store to the backing store. The apparatus also includes a baseline back-up element that stores archive copies of a set of selected data files. A full back-up element stores archive copies of those files that, (1) were originally copied to the baseline back-up set but have since changed, or (2) are not otherwise within the baseline back-up set. For those files which were originally copied to the baseline back-up set and which have not changed, the full back-up element stores pointers indicating locations of the respective files in the baseline back-up set.