Fly-by XOR for generating parity for data gleaned from a bus

In a system having a processor, a memory, a memory bus coupling said processor and said memory, a plurality of mass storage devices, and a secondary bus coupling said plurality of mass storage devices to said memory bus, a method including the steps of

• initiating a DMA operation between at least one of said plurality of mass storage devices and a buffer location in said memory;
• monitoring said secondary bus for a plurality of addresses in said buffer location;
• copying data associated with said plurality of addresses into an XOR buffer without interfering with said DMA operation;
• and
• accumulating a result of an XOR operation for said data.

A system including

• a processor, a memory bus coupled to said processor, and a memory coupled to said memory bus;
• a plurality of mass storage devices and a secondary bus coupling said plurality of mass storage devices to said memory bus, whereby said secondary bus is used for transferring data to and from one of said plurality of mass storage devices;
• and
• an element coupled to said secondary bus, said element including a means for copying data transferred to and from one of said plurality of mass storage devices without interfering with said operation of transferring, and including a means for accumulating a result of an XOR operation for said data.