Abstract: A data storage system randomly determines a start offset at which to write objects to a storage medium. For updated blocks of the object, e.g., for blocks written during copy-on-write as part of a point-in-time snapshot, the updated block is written in the region of the original file or as close thereto as possible to achieve “virtual contiguity”. Subsequent reads of the object read entire region containing both the object and, potentially, “chaff” data other than the object. The “chaff” data is discarded by the I/O system or file system using, e.g., a bit mask, subsequent to the read.

Abstract: Digital data objects containing unused space are reconfigured to facilitate more efficient compression of the data objects. First, a determination is made whether the data object contains regions of unused storage space. Such space may represent deleted files, corrupted data, expired data, etc. If regions of unused storage space exist, they are replaced with a predetermined bit pattern. This bit pattern is specifically chosen so that, if provided as input to a predetermined digital data compression process, it would be compressed with a predetermined predicted compression efficiency. For example, the bit pattern may comprise a repeating sequence of binary zeros, which is optimally compressed by most known compression processes. After reconfiguration of the data object, the data object may be provided as input to the compression process and compressed.

Abstract: Extensions to a database system provide linkage between data in the database system and files in a system for filing data which is external to the database system ("the filing system"). The linkage includes an external file reference (efr) data type which is defined in the database system for reference to files that are stored in the filing system. When entries are made in the database system that include efr data-type references to files in the filing system, control information is provided by the database system to the filing system. The control information causes the filing system to control processing of referenced files according to referential constraints established in the database system.