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: 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 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: 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: Disclosed is a method, system, program, and data structure for providing a shadow copy of data storage areas in a primary site to data storage areas in a secondary site. A definition is made of storage areas in the primary site having data to be shadowed and corresponding storage areas in the secondary site to shadow data at the storage areas in the primary site. A shadow pair comprises one primary storage area and one secondary storage area that shadows data for the primary storage area in the pair. A standard data transfer interface protocol command, such as a SCSI or Fibre Channel command, is used to configure status storage areas in the secondary site to provide status information and data for each primary and secondary storage area. A write command in the standard data transfer interface protocol is then used to write status information to the status storage areas indicating status of the shadowed data at the secondary storage areas in the pairs.

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: 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 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 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: The invention enables reduction of latency time for receipt of data which has been requested from a disk system. The method enables use of a read command which enables a cache memory output to occur only when the read command has been completed. The method of the invention initially receives a read request from a host processor for a number of data blocks on a disk track (referred to as requested blocks), the requested blocks being a subset of blocks stored in the disk track. If the requested blocks are not already stored in a cache memory, the method constructs at least a first command to transfer the track to cache memory, the first command enabling identification of a last data block of the requested blocks. A second command is also prepared to transfer the track to cache memory, the second command enabling identification of the last block of the remaining set of blocks in the track.

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 program for processing data access requests, such as read requests, to a storage location maintained in both a first storage, such as a cache, area and second storage area, such as a disk drive, during a destage operation. A destage operation is granted access to the storage location to destage data from the storage location in the first storage area to the second storage area. During the destage operation, a data access request is granted access to the storage location.

Abstract: Provided are a system, method, program, and data structure for processing a request for data in a first format that is superimposed on blocks of data stored in a second format in a storage device. A data structure for a storage unit in the first format including the requested data is accessed. There is one data structure for each storage unit in the first format being accessed. Further, at least one cache page storing blocks of data in the second format is needed to store one storage unit in the first format. A determination is made of one or more storage blocks in the second format that include the requested data. A determination is also made as to whether the storage unit data structure includes a pointer to a control block for a cache page that would include the determined storage blocks in the second format.

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 defining paths for a computer to use to send commands to execute with respect to storage regions in a storage device that are accessible through at least two controllers. For each storage region, one controller is designated as a preferred controller and another as a non-preferred controller. The computer initially sends a command to be executed with respect to a target storage region to the preferred controller for the target storage region and sends the command to the non-preferred controller for the target storage region if the preferred controller cannot execute the command against the target storage region. In response to the non-preferred controller receiving at least one command for the target storage region, the designation is modified to make a current preferred controller the non-preferred controller for the target storage region and a current non-preferred controller the preferred controller for the target storage region.

Abstract: Disclosed is a system for caching data. After determining a sequential access of a first memory area, such as a direct access storage device (DASD), a processing unit stages a group of data sets from the first memory area to a second memory, such as cache. The processing unit processes a data access request (DAR) for data sets in the first memory area that are included in the sequential access and reads the requested data sets from the second memory area. The processing unit determines trigger data set from a plurality of trigger data sets based on a trigger data set criteria. The processing unit then stages a next group of data sets from the first memory area to the second memory area in response to reading the determined trigger data set.

Abstract: A method and apparatus for improving write performance in a disk array is disclosed. The invention avoids unnecessary track grouping 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, a determination of whether the write request involves a full track write is made and a cache destage is subsequently executed based on the analysis of the full track write counter for tracks in a stripe of tracks associated with the write request. The full track write counter is not incremented when the write to cache is not a full track write. When the write to cache is a full track write, a previous track full track count is fetched, 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 1.

Abstract: Disclosed is a system for managing data in cache. A list of data entries in a first memory area has a first end and a second end, such as a most recently used (MRU) end and least recently used (LRU) end. A first pointer addresses a data entry in the list and a second pointer addresses another data entry in the list that is not at the first and second ends. Data from a second memory area is provided to add to the list. A determination is made as to whether the provided data to add to the list is one of a first type and second type of data, such as sequentially accessed data or non-sequentially accessed data. The provided data is stored in the first memory area as a new data entry in the list. The first pointer is modified to address the new data entry after determining that the provided data is of the first type. After determining that the provided data is of the second type, the second pointer is processed to determine where to add the new data entry to the list between the first and second ends.

Abstract: Disclosed is a cache management scheme using multiple data structure. A first and second data structures, such as linked lists, indicate data entries in a cache. Each data structure has a most recently used (MRU) entry, a least recently used (LRU) entry, and a time value associated with each data entry indicating a time the data entry was indicated as added to the MRU entry of the data structure. A processing unit receives a new data entry. In response, the processing unit processes the first and second data structures to determine a LRU data entry in each data structure and selects from the determined LRU data entries the LRU data entry that is the least recently used. The processing unit then demotes the selected LRU data entry from the cache and data structure including the selected data entry. The processing unit adds the new data entry to the cache and indicates the new data entry as located at the MRU entry of one of the first and second data structures.

Abstract: A system for providing multiple hosts with concurrent access to cached data by selectively generating, maintaining, modifying, and consolidating multiple versions of data items in cache memory to efficiently accommodate data access requests by the hosts. Data associated with a logical track is represented in cache by a number of cache track image parts. Each part represents one or more records in cache, where multiple parts may exist in cache for the same logical track. The provision of multiple parts supports concurrent access by multiple operations or "processes" to data associated with a track. Namely, each part is given a "status" selected from a predetermined catalog of statuses; the assigned status thus establishes the permissible manner of accessing that part. Depending upon a part's status, the part may be used by one process (e.g. Read) or by multiple processes concurrently (e.g. Read and Destage). Other part statuses dedicate a part to a single process (e.g. Write).