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: The present invention is a method and system for upgrading drive firmware on a drive within a distributed data storage system in a manner that is transparent and non-disruptive to the host system operations. The method and system allow for normal read and write operations to occur during the firmware upgrade process, even while the primary disk drive is off-line, through alteration of the controller read and write policies. A mapping file is created on a temporary storage device to reduce the necessary time period of the upgrade process. This time period is further reduced in a mirrored storage system or in a system having a spare drive, where a logging file is created to store the data diverted from the primary disk drive during the upgrade process. An advantage is the ability to maintain storage system redundancy during the upgrade process.

Abstract: A computer assembly is disclosed. The computer assembly comprises a chassis and a mounting module rigidly coupled to the chassis. The mounting module is for cooling the computer assembly when in operation. The computer assembly includes at least one circuit board suspended from the module. The at least one circuit board has a known orientation relative to the module and the at least one circuit board has a variable orientation relative to the chassis. A system and method in accordance with the present invention provides a stable mounting for the cooling system that includes a large heat sink. The method and system in accordance with the present invention prevents the disturbance of the critical alignment of the printed circuit board with the heatsink from shock and vibration loading.

Abstract: The present invention relates to a snapshot system for a data storage system including a host that communicates with a cache memory, source storage, target storage, and metadata, including a source storage for active data, a target storage to store migrated snapshot data, first metadata (e.g., bitmaps and log files with pointers) to indicate when and to locate where the first snapshot data is in the target storage, and second metadata (e.g., bitmaps and log files pointers) to indicate when and to locate where the second snapshot data is in the target storage wherein the first metadata and the second metadata locate the same snapshot data in the target storage.

Abstract: A method, apparatus and program storage device for maintaining data consistency and cache coherency during communications failures between nodes in a remote mirror pair. A link between a mirror pair of storage systems is monitored. During a link failure between a first storage system and a second storage systems, reads and writes on the first and second storage systems are independently performed and write data and associated timestamps are maintained for the write data for each write in a queue on the first and second storage system. After link reestablishment, volume sets on the first and second storage systems are resynchronized using write data and associated timestamps.

Abstract: The present invention relates to a cache memory management system suitable for use with snapshot applications. The system includes a cache directory including a hash table, hash table elements, cache line descriptors, and cache line functional pointers, and a cache manager running a hashing function that converts a request for data from an application to an index to a first hash table pointer in the hash table. The first hash table pointer in turn points to a first hash table element in a linked list of hash table elements where one of the hash table elements of the linked list of hash table elements points to a first cache line descriptor in the cache directory and a cache memory including a plurality of cache lines, wherein the first cache line descriptor has a one-to-one association with a first cache line.

Abstract: A method, apparatus and program storage device for allowing continuous availability of data during volume set failures in a mirrored environment. Continuous servicing of input/output request for a volume set having failed on a primary array using either portions of the failed volume set or a mirrored volume set is provided. A determination is made whether the failed volume set can service the input/output request and continuous data availability is provided by using the failed volume set to process the input/output request when the failed volume set can service the input/output request, else using a remote mirrored volume set to process the input/output request.

Abstract: The invention relates to host caching in data storage systems. In an embodiment, the invention provides a first host and a second host, each having memory. The host memory includes nonvolatile and volatile portions available for cache. Each host logically owns its volatile memory and the other host's nonvolatile memory. By assigning ownership in this way data can be transmitted between the hosts with little communication overhead. In addition, if the first host fails between write acknowledgment and destaging the write data, the write data is safely stored in the second nonvolatile memory of the second host. Thus, the second host can destage the data from the second nonvolatile memory. In addition, the host cache writes and reads the data rapidly by its nature.

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, and program for caching data. Data from a device, such as a volatile memory device or non-volatile storage device, is maintained in entries in a cache. For each entry in cache, a variable indicates both a time when the cache entry was last accessed and a frequency of accesses to the cache entry. The variable is used in determining which entry to denote from cache to make room for subsequent entries.

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: The present invention is a method and system for upgrading drive firmware on a drive within a distributed data storage system in a manner that is transparent and non-disruptive to the host system operations. The method and system allow for normal read and write operations to occur during the firmware upgrade process, even while the primary disk drive is off-line, through alteration of the controller read and write policies. A mapping file is created on a temporary storage device to reduce the necessary time period of the upgrade process. This time period is further reduced in a mirrored storage system or in a system having a spare drive, where a logging file is created to store the data diverted from the primary disk drive during the upgrade process. An advantage is the ability to maintain storage system redundancy during the upgrade process.

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: 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.