the original four hard disks 560 561 562 and 563 as well as enough memory to support intermediate calculations and or swap space the number of data blocks to read from each disk may be selected based on one or more criteria such as but not limited to the largest number of data blocks that may be read in a single hard disk access command the size of the memory module and or hard disk input output considerations in this example an in buffer expansion is executed in memory module 570 creating new redundancy blocks and discarding old redundancy blocks data blocks are not re arranged in the memory module 570 to correspond to the target spatial position and or target order of the data blocks on target raid devices 560 561 562 563 and 564 this example highlights a possible benefit provided by a random access memory buffer in this example a controller manages copying the data blocks from the memory module 570 to target hard disks 560 561 562 563 and 564 in this example the memory module was large enough to manage the entire contents of raid group 560 and complete the raid operation in a single pass in some examples of a fast access buffer according to the current invention access to data during maintenance and or raid operations may be enabled.