1. A computing device comprising: a processor; one or more computer readable storage media, coupled to the processor, storing multiple modules for execution by the processor, the multiple modules including: a copy set activation module that selects which of multiple copy sets stored on the one or more computer readable storage media to access, each copy set comprising a grouping of data units configured to provide data in response to a particular scenario, at least some of the data units in each copy set also included in a master set; a copy set creation module that generates new copy sets to be added to the multiple copy sets, each new copy set having at least some of the same data units as other copy sets of the multiple copy sets; and a copy set update module that controls updating of the multiple copy sets when one or more data units in at least one of the multiple copy sets or in the master set is modified, wherein the size of at least some of the data units is selected based on at least one factor selected from a group comprising: a disk page size of at least a first of the one or more computer readable storage media that is different than a disk block size for the first computer readable storage media; a size of a memory page; a size of a unit of data used by a file system of at least one of the one or more computer readable storage media; or a cluster size used by a file system of at least one of the one or more computer readable storage media.