Abstract: A RAID disk array controller implements a write mask to support partial-stripe updates from a host system without expensive RAM to RAM copying and repeated disk accesses to assemble the updated stripe. New data from the host is transferred into a single buffer and a local processor tracks—by setting bits in the write mask—which segments of the target stripe are updated. The disk array is accessed to transfer the target stripe into the same buffer, but the buffer memory write enable is inhibited—responsive to the write mask—during transfer of the segments that were updated by the host. The complete, updated stripe is thus formed in a single buffer for parity calculations and write to the disk array.

Abstract: A RAID disk array controller [(FIG. 7)] implements a write mask 16 to support partial-stripe updates [(FIG. 4)] from a host system [60] without expensive RAM to RAM copying and repeated disk accesses to assemble the updated stripe. New data from the host [20,22] is transferred into a single buffer [14,40] and a local processor [80] tracks—by setting bits [30,32] in the write mask—which segments of the target stripe are updated. The disk array is accessed to transfer the target stripe into the same buffer [40], but the buffer memory write enable [58] is inhibited—responsive to the write mask [52]—during transfer of the segments that were updated by the host. The complete, updated stripe is thus formed in a single buffer for parity calculations and write to the disk array.

Abstract: A RAID storage device controller provides a host interface for interfacing the controller to a host system bus. The host interface is isolated from the attached storage devices, for example IDE disk drives, so that the actual attached drives are not limited in number or interface protocol. Various device ports can be implemented, and various RAID strategies, e.g., level 3 and level 5, can be used. In all the cases, the host interface provides a standard, uniform interface to the host, namely an ATA interface, and preferably a dual channel ATA interface. The host interface emulates the ATA single or dual channel interface and emulates one or two attached IDE devices per channel, regardless of the actual number of devices physically connected to the controller. Thus, for example, five or seven IDE drives can be deployed in RAID level 5 protocol without changing the standard BIOS in a PCI host machine. Thus the RAID controller is transparent relative to a standard dual channel ATA controller board.

Abstract: Method and apparatus to effect synchronous data transfers in a disk controller, for example to and from a common buffer (52), when the data transfers to and from the individual disk drives (12,20) are actually asynchronous. A FIFO memory (26,28) is provided in the controller for each disk drive. Asynchronous data transfers between each drive and the corresponding FIFO use the timing provided by the respective drive (interfaces 16,24); whereas data transfers on the buffer side of the FIFOs (46,48) are effected synchronously (44,72). The availability of synchronous data transfers enables “on the fly” generation of redundancy information (FIG. 3) (in the disk write direction) and “on the fly” regeneration of missing data in the read direction (FIG. 4).

Abstract: A RAID storage device controller provides a host interface for interfacing the controller to a host system bus. The host interface is isolated from the attached storage devices, for example IDE disk drives, so that the actual attached drives are not limited in number or interface protocol. Various device ports can be implemented, and various RAID strategies, e.g. level 3 and level 5, can be used. In all the cases, the host interface provides a standard, uniform interface to the host, namely an ATA interface, and preferably a dual channel ATA interface. The host interface emulates the ATA single or dual channel interface and emulates one or two attached IDE devices per channel, regardless of the actual number of devices physically connected to the controller. Thus, for example, five or seven IDE drives can be deployed in RAID level 5 protocol without changing the standard BIOS in a PCI host machine. Thus the RAID controller is transparent relative to a standard dual channel ATA controller board.