Abstract: Lun communications between a storage server and a storage subsystem for a particular lun are assigned both a current path and an alternate path. Lun communications use the current path unless the current path is determined to be faulty. Path errors may result in the storage server determining a path to be faulty. If the current path for a lun communication is determined to be faulty, then the lun communications will be sent through the alternate path so long as the alternate path is determined to be reliable. Over time, a path previously determined to be faulty may recover and be used again for lun communications.

Abstract: A mass data storage system including a hard disk drive comprising heads and platter surfaces determines when a head of the disk is faulty and the disk continues to operate as a partially failed disk with respect to the remaining heads which are not faulty. A striped parity disk array comprises disks capable of operating as partially failed disks allows copying of data from the platter surfaces not associated with a faulty head of a partially failed disk to a spare disk which reduces the amount of data that must be rebuilt in the rebuild process, thereby reducing the amount of time the array spends in degraded mode exposed to a total loss of data caused by a subsequent disk failure.

Abstract: A source application reads a body of data in data block sized units and calculates a checksum value for each data block before sending the data block, the calculated checksum value and the identifier. Upon receipt, a destination application independently calculates a checksum value for each received data block and compares the two checksums. Non-matching checksums indicate a network-induced error in the data block. Identifiers for the erroneous data blocks are transmitted to the source application after all of the data blocks have been initially transmitted. The source application thereafter resends only those data blocks identified. The destination application repeats the process of comparing checksums and transmitting identifiers to the source application until all of the data blocks of the body of data have been correctly received, and then uses the data blocks to recreate the body of data.

Abstract: The input/output (I/O) performance of a hard disk drive in a mass storage computer system is evaluated to maintain efficiency by addressing I/O commands to sectors of the disk drive, evaluating the execution of the I/O commands to the sectors to obtain performance information for the sectors to which the I/O commands are addressed, comparing the performance information to a predetermined I/O performance criterion, and identifying any impaired sectors in which the performance information indicates less than the predetermined I/O performance criterion. Thereafter, further I/O commands to the impaired sectors are avoided.

Abstract: A nonvolatile system memory of a server of a network file computer system temporarily stores data received from client computers prior to the data being stored on a mass storage device. A single copy of the data and pointers which corresponds to the memory addresses of the data are stored in a temporary memory storage portion, preferably partitioned from nonvolatile system memory. The pointers are used to access the data to enable the transfer and writing of the data from the temporary memory storage to the mass storage device. Writing the data occurs during the normal operation of the network file computer system or after an unclean shutdown. The use of the pointers increases the performance of the network file computer system by conserving system memory storage space and reducing system memory traffic.

Abstract: A mobile facility has a fixed frame, an expandable roof section, an expandable floor section, and an expandable side section. Interior space within the mobile facility is expanded by expanding the expandable roof section, the expandable floor section and the expandable side section.