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: When a computer system is upgraded, such as by adding a more advanced processor chip and/or a new operating system, a different page size may be employed. The page size is altered for data previously stored in a storage medium such as a hard disk in the computer system, without removing all of the data from the medium and rewriting it. Data is stored in the medium in blocks or sectors which have headers defining the block. Also, tables define memory objects and segments, and locate virtual memory addresses in physical memory. The headers and/or tables can be changed without rewriting all of the data in the sectors or pages in physical memory, so the page size is changed to accommodate the new system components, without excessive burden on system hardware or undue expenditure of time.