Abstract: A method of selecting candidates for data cluster duplication that can be used as an alternative or as an addition to existing duplication techniques. The method determines a read temperature of a data cluster. If the read temperature of the data cluster exceeds a threshold value, a write temperature of the data cluster is determined. If the write temperature of the data cluster is below a threshold value the cluster is selected for duplication.

Abstract: A system and method for managing a domain comprised of a plurality of database systems, wherein each of the database systems performs database queries to retrieve data stored by the database systems. There are one or more virtual regulators for managing the domain and one or more closed-loop system management (CLSM) regulators for managing each of the database systems in the domain. Both the virtual regulators and CLSM regulators perform parallel virtual optimization of the database queries performed by the database systems.

Abstract: A system and method for managing one or more database systems, wherein the database systems perform database queries to retrieve data stored by the database systems. One or more regulators are used for managing the database systems, wherein the regulators monitor workload priority influenced data temperature in order to allocate resources for the systems. The data temperature is a measure of physical accesses to logical data, and the workload priority is used to further define data temperature, in order to optimize data storage placement and data access decisions.

Abstract: Techniques for selective compression of database information are presented. Selective first portions of a field associated with a database table are identified along with metadata associated with the database table. The first portions and the metadata are then compressed by selecting one or more compression algorithms in response to compression capabilities associated with the algorithms.

Abstract: A system and method for managing database systems, wherein the database systems perform database queries to retrieve data stored by the database systems. One or more regulators are used for managing the database systems, wherein a database tuning agent function of the regulator uses statistics on physical and logical data access in order to perform automated block size management for database objects.

Abstract: A method and system of reading data from a storage device. The storage device includes a plurality of physical storage extents. One or more of the storage extents is/are associated with a “void extent” indicator, a void extent being an extent that was the target of an unsuccessful write completion. In one technique a request is received to read the data from the storage device. The physical storage extent(s) on which the requested data is stored is located. If one of the located storage extents has an associated void extent indicator then a read error is returned. In a further technique, a request is received to read the data from the storage device. The physical storage extent(s) on which the requested data is stored is located. The data from the located storage extent(s) is retrieved if the read request is a diagnostic read and if the or one of the located storage extents has an associated void extent indicator.

Abstract: A method and system for allocating storage space on a storage device to a requesting entity. The storage device includes a set of extents. An allocation map is maintained in computer memory. The allocation map has a plurality of map blocks, the map blocks each having a plurality of map entries. The map entries include respective logical extent identifiers, physical extent information and obsolete indicators. An invalid extent logical identifier represents a free extent and a valid extent identifier represents a prior allocated extent. An obsolete indicator marks a map entry as either current or obsolete. In one technique an extent allocation request is received from the requesting entity. A first map block is selected having a first map entry marked as obsolete. A second map block is selected having a second map entry not marked as obsolete. Physical extent information is copied from the second map entry to the first map entry. The logical extent identifier is assigned to the first map entry.

Abstract: A method and system for allocating storage space from storage devices within a computer system. The storage devices are grouped into respective homogeneous sets in which identical storage devices are included in the same homogeneous set. In accordance with the method and system, following receipt of an allocation request for storage space one or more stored response values are checked, the response values associated with at least one homogeneous set. The stored value or values represent the average response time of storage devices within the set. The homogenous set with the lowest average response time is selected. One or more stored allocation values are then checked that are associated with at least one storage device within the selected homogeneous set. The stored allocation value or values represent the current allocations of the associated storage device.

Abstract: A system and method for use in retrieving rows of data from at least one table in a database system comprising tables of data stored on one or more storage facilities and managed by one or more processing units. A plurality of samples retrieved from a table in the database are maintained in computer memory, the samples associated with age data representing the order in which the samples were retrieved. The number of samples (S) required to be maintained that are representative of the table is calculated. The number of samples (A) to remove from the samples maintained in computer memory is calculated. The A oldest samples are removed from the samples maintained in computer memory. The number of samples (R) to retrieve from the table is calculated. R new samples are retrieved from the table. The R new samples are stored with the samples maintained in computer memory.