Abstract: A RAID or RAIT type data storage array such as a single tape RAIT includes storage elements storing data blocks and a parity block based on the data blocks. The array reads the data blocks sequentially from respective storage devices. The array determines if any of the data blocks are bad as the data blocks are being read. The array accumulates the parity of good data blocks as the data blocks are being read. A bad data block is reconstructed from the accumulated parity of the good data blocks and the parity block.

Abstract: A method is provided for enabling a computer that processes data formatted in a first format to read a data unit that is formatted in a second format from a storage subsystem that is capable of storing data in either the first format or the second format. The method comprises the steps of dispatching, from the computer to the storage subsystem, a command for the storage subsystem to report a data length of the data unit; sending, from the storage subsystem to the computer, a value of the data length that enables the computer to determine whether the data unit is in the first format or in the second format and prepare for receipt of the data unit in the first format or the second format, having the indicated data length; dispatching, from the computer to the storage subsystem, a command for the storage subsystem to forward the data unit to the computer; and sending the data unit from the storage subsystem to the computer.

Abstract: A system and method for allocating tape drives for multi-cartridge files achieves most of the benefits of allocating two tape drives without the cost of a mostly idle tape drive. The system and method includes allocating a first tape drive to process a first tape cartridge and then allocating a second tape drive to process a second tape cartridge while the first tape cartridge is rewinding after being processed. The second tape cartridge is then mounted into the second tape drive while the first tape cartridge is being rewound. The first tape cartridge is then dismounted from the first tape drive and the second tape drive begins processing the second tape cartridge. The operation is then continued by using other tape drives, which may include the first and second tape drives, to process the tape cartridges. The processing includes writing respective parts of a file to the tape cartridges to store a complete multi-cartridge file.