Abstract: Provided are a system, program, and data structure for selecting one of multiple data paths to a device. A selection is made of one of multiple paths indicated as enabled to transmit data. A path is indicated as enabled or disabled. Transfer time data is gathered for each enabled path capable of being selected. Paths having transfer time data satisfying a threshold are indicated as disabled. Paths indicated as disabled are not capable of being selected to use to transmit data.

Abstract: Provided are a system, program, and data structure for selecting one of multiple data paths to a device. A selection is made of one of multiple paths indicated as enabled to transmit data. A path is indicated as enabled or disabled. Transfer time data is gathered for each enabled path capable of being selected. Paths having transfer time data satisfying a threshold are indicated as disabled. Paths indicated as disabled are not capable of being selected to use to transmit data.

Abstract: Disclosed is a method, system, program, and data structure for selecting one of multiple data paths to a device. A selection is made of one of multiple paths indicated as enabled to transmit data. A path is indicated as enabled or disabled. Transfer time data is gathered for each enabled path capable of being selected. Paths having transfer time data satisfying a threshold are indicated as disabled. Paths indicated as disabled are not capable of being selected to use to transmit data.

Abstract: The present invention is a method and system for translating method calls to version-specified method calls. An interface to an underlying object is provided. Applications communicating with the underlying object use the interface. The interface is separate from the underlying object. Version-specific underlying objects are generated. Each one of the version-specific underlying objects is a different version of the underlying object. A plurality of translation objects, one for each version-specific underlying object, are generated for communicating between the interface and each one of the version-specific underlying objects. A translation object is used for translating an interface method call invoked on the interface to a version-specific method call for the underlying object for each version of the underlying object. All translation objects are generated from a single proxy class and a single invocation handler class.

Abstract: Disclosed is a method, system, program, and data structure for updating code in a first and second controllers. The first and second controllers are capable of accessing storage regions in a storage device. The first controller receives a code update and signals the second controller. Access to the first controller is disabled and the code update is applied to the first controller. In response to the signaling, the second controller receives commands directed to all of the storage regions during the code update to the first controller.

Abstract: Provided is a computer implemented method, system, and program for implementing for implementing a remote method call. Remote objects and at least one proxy object are generated, where each proxy object corresponds to one remote object. Data from the remote object is included into the proxy object. A call to a method on one proxy object is processed and the method is executed. The method is one of a plurality of methods, wherein at least one of the plurality of methods comprises a local method including code to perform method operations on the proxy object without going to the remote object and at least one other of the plurality of methods comprises a remote method including code to perform method operations on the remote object.

Abstract: Disclosed is a method, system, and article of manufacture for processing modified meta data for data recovery operations. The meta data provides information on user data maintained in a storage device. The system determines whether meta data tracks maintained in a cache were modified and indicates in a non-volatile memory that the determined meta data tracks were modified. Data recovery operations may be initiated as a result of a system failure, such as a warmstart or coldstart recovery. During such data recovery operations, the system processes the non-volatile memory and the indications of modified meta data tracks therein to rebuild lost meta data tracks in the cache.

Abstract: Disclosed is a method, system, and article of manufacture for managing meta data. The meta data provides information on data maintained in a storage device. The system receives a request for meta data from a process and determines whether the requested meta data is in cache. After determining that the requested meta data is not in cache, the system determines whether there are a sufficient number of allocatable segments in cache to stage in the meta data and allocates segments in cache to store the meta data after determining that there are enough allocatable segments in cache. The system stages the requested meta data into the allocated segments. Alternatively, after determining that the requested meta data is in cache, the system determines whether a second process has exclusive access to the meta data in cache. After determining that the second process does not have exclusive access, the system indicates to the first process that access to the meta data is permitted.

Abstract: Provided is a method, system, and program for determining a configuration of a logical array including a plurality of storage devices. A selection of a number of storage devices is received to include in the logical array. A determination is made of a number of groups in which to include the selected number of storage devices, wherein each group includes at least one storage device maintaining user data and parity data for the user data in the group. Determining an assignment of the selected number of storage devices to the determined number of groups and allocating the storage devices to the determined number of groups according to the determined assignment.

Abstract: Disclosed is a method, system, and data structures for updating data in a storage device. An update to one or more blocks of customer data at addresses in the storage device is received. For each block of data to update, metadata is generated indicating the address of the block in the storage device and an error checking code that is capable of being used to determine whether the customer data in the block has changed. For each block of data to update, the block of data to update and the metadata for the block are written to cache. Further, for each block of data to update, the block of data and the metadata are transferred for the block from the cache to the storage device. The metadata may be used during power loss and recovery.

Abstract: Provided is a method, system, and program for superimposing a data record in a first data format onto a storage space in a second data format. A plurality of control blocks are built in memory indicating operations to perform to transfer components of the data record in the first data format to locations in memory in the second data format. A data transfer device is signaled to access the control blocks built in the memory. The data transfer device accesses the control blocks in the memory and then transfers components of the data record in the first data format to the memory to be stored in the second data format according to the operations indicated in the control blocks.

Abstract: Disclosed is a method, system, program, and data structure for executing write operations. A first number of write operations is initiated. Performance data is gathered indicating a total time for a second number of the initiated write operations to complete. After at least one initiated write operation has completed, at least one additional write operation is initiated if a number of outstanding write operations is less than a maximum number of write operations. The maximum number of write operations is adjusted if the performance data meets at least one threshold.

Abstract: Disclosed is a method, system, program, and data structures for transferring data to a requesting application. A request is received for one or more blocks of data at contiguous addresses in a storage device. Each block of data includes customer data and metadata indicating the address of the block in the storage device and an error checking code that is capable of being used to determine whether the customer data in the block has changed. For each requested block, a determination is made as to whether the address of the block of data in the metadata and the requested address match. Further, for each requested block, an operation is performed on the customer data in the block and the error checking code to determine whether the customer data has changed. The requested block is transferred to the requesting application if the address of the block in the metadata and requested address match and the customer data has not changed.

Abstract: A method and apparatus for improving write performance in a disk array, wherein unnecessary track grouping is avoided during writes, by using a full track write counter. When a write request is received, the full track write counter for tracks in a stripe of tracks associated with the write request is analyzed to determine whether the write request involves a full track write. A cache destage is subsequently executed based on the analysis. When the write to cache is a full track write, a previous track full track count is fetched from a previous track's full write counter, a full track count of the tracks associated with the write request are set to be equal to the minimum of either the stripe width or the previous track's full track count plus one.

Abstract: Provided is a method, system, and program for configuring an attached storage device through a storage adaptor. The storage adaptor includes an initialization routine to generate initialization data to write to the storage device when adding storage space in the storage device to a system. A request is received to add storage space to the system. A command is transmitted to the storage adaptor capable of inhibiting the storage adaptor from performing the initialization routine. Initialization data is generated for the storage space and transmitted to the storage adaptor to write to the storage space to initialize the storage space.

Abstract: Disclosed is a system and method for caching data. A processor receives data from a host to modify a track in a first storage device. The processor stores a copy of the modified data in a cache and indicates in a second storage device the tracks for which there is modified data in cache. During data recovery operations, the processor processes the second storage device and data therein to determine the tracks for which there was modified data in cache. The processor then marks the determined tracks as failed to prevent data at the determined tracks in the first storage device from being returned in response to a read request until the failure is resolved. In further embodiments, in response to detecting a partial failure within the storage system, the processor would scan the cache to determine tracks for which there is modified data stored in the cache.

Abstract: Implementations describe the expansion of storage space in an array of storage units. The storage space formed by the storage units is configured as logical units to store data. Storage units are added to the array to form an expanded storage space. The storage units in the array prior to the addition of the storage units are in a pre-expansion storage space. At least one additional logical unit is configured in the expanded storage space such that the logical units existing prior to the addition of the storage units in the pre-expansion storage space are not affected by the logical units configured in the expanded storage space.

Abstract: A method, system, program, and data structure for restricting host access to at least one logical device. Each logical device comprises a section of physical storage space that is non-overlapping with the physical storage space associated with other logical devices. At least one logical device and at least one host are assigned to a cluster group. A cluster group is defined such that hosts that are not in a particular cluster group cannot access the logical devices that are assigned to the cluster group. Further, within each cluster group, a logical number is assigned to each logical device in the cluster group such that no host member of that cluster group uses the assigned logical number to access another logical device. The hosts in the cluster group use the logical number to access the logical device to which the logical number is assigned.

Abstract: Disclosed is a method, system, program, and data structures for mapping logical units, such as logical unit numbers (LUNs), to a storage space comprised of at least one array of storage units, e.g., hard disk drives. Configuration information stored in one array indicating a first mapping of logical units to storage locations in the array is read. A second mapping of logical units to storage locations in multiple arrays is generated using the configuration information read from the array. Each logical unit is assigned to only one of the arrays.

Abstract: Disclosed is a method, system, program, and data structure for selecting a path to one of at least two controllers. Each controller is capable of providing access to storage areas, such as Logical Unit Numbers (LUNs). Path information is received from the controllers indicating a preferred controller to use to access each storage area. An input/output (I/O) command directed to a target storage area is processed and the I/O command is directed to the controller indicated in the path information as the preferred controller for the target storage area. The controller receiving the I/O command executes the I/O command against the target storage area. The path information to the storage controllers providing access to the storage areas is encoded with information designating one controller as the preferred controller and another as a non-preferred controller. The encoded path information is returned to a requesting computer.