Abstract: A method backs up computer data by organizing update requests into groups. All update requests in one group complete concurrently before requests of a subsequent group complete.

Abstract: An apparatus and method provides the capability of mirroring storage from a primary system to a mirrored system in a way that uses parallelism in the mirrored system to maximize the efficiency of writing data to the mirrored storage for operations that do not conflict while serializing operations that do conflict. The mirroring of the present invention is “logical mirroring”, which does not require identical disk drives, and which supports mirroring between geographically remote locations to protect against catastrophic site failure. Parallelism is achieved in the mirrored system by dividing the virtual address space into multiple ranges, and by assigning a group of tasks to each range. When an operation is received on the mirrored system, the virtual address range that the operation affects is determined, and the operation is then delegated to the task group that corresponds to the affected virtual address range. By dividing the virtual address space into ranges, tasks in different ranges (i.e.

Abstract: An apparatus, program product and method for estimating the number of keys within an index key range over an index using page pointers to pages in the index comprises a program configured for scanning the index, from a divergence point of the key range, until a page pointer is found and incrementing a counter for each found page pointer. The program is further configured for determining if the page pointer points to a leaf page in the index, and if it does, continuing the scan to find the next page pointer without going to the corresponding leaf page. Otherwise, the program continues the scan to find the next page pointer and continues the scan for page pointers and increments the counter until the index is scanned for the entire key range. Upon completion of the scan, the program determines an estimate of the number of keys utilizing the counter.

Abstract: A method for partitioning keys onto radix tree logical pages and a parallel index page build algorithm in order to provide radix tree build speedup proportional to the number of processors on the system and controlled efficient page utilization. Also, since keys are intelligently partitioned so that a complete set of keys is inserted into a logical page, there is no page overflow during the tree construction and thus page splitting is eliminated. Since radix index trees are really groups of logical pages in which each logical page contains a small tree, the tree is built (with respect to the logical pages) from the bottom up, while within each individual logical page the tree is constructed from the top down. The space required for a logical page is pre-allocated to allow construction of limbs to begin without waiting for the build of their underlying pages to complete.