Abstract: The invention relates to management of I/O in data storage systems. In an embodiment, the invention provides a data storage subsystem processing I/O requests each having a priority, comprising a processor, a memory coupled to the processor, a disk array, an array controller coupled to the processor and the disk array, a network interface, coupled to the processor, to receive an I/O request with a priority, and a program in the memory for managing the I/O request based on the priority, a clip level of the priority, the total workload in the data storage subsystem, and processing I/O requests based on priority, workload clip levels, and fairness levels. The invention also contemplates the use of static and dynamic adjusted clip levels.

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: The present invention relates to systems and methods of asynchronous data replication. In an embodiment, the system includes a primary host that asynchronously transmits write and sync commands where each write and sync command includes a data set ID and a sequence number. A secondary host coupled to the primary host receives the write and sync commands out of order, tracks receipt of write and sync commands, and after receipt of the write and sync commands of the data set writes blocks associated with the write commands to data storage coupled to the secondary host.

Abstract: The invention relates to management of I/O in data storage systems. In an embodiment, the invention provides a data storage subsystem processing I/O requests each having a priority, comprising a processor, a memory coupled to the processor, a disk array, an array controller coupled to the processor and the disk array, a network interface, coupled to the processor, to receive an I/O request with a priority, and a program in the memory for managing the I/O request based on the priority, a clip level of the priority, the total workload in the data storage subystem, and processing I/O requests based on priority, workload clip levels, and fairness levels. The invention also contemplates the use of static and dynamic adjusted clip levels.

Abstract: A fault tolerant synchronized virtual memory manager for use in a load sharing environment manages memory allocation, memory mapping, and memory sharing in a first processor, while maintaining synchronization of the memory space of the first processor with the memory space of at least one partner processor. In one embodiment, synchronization is maintained via paging synchronization messages such as a space request message, an allocate memory message, a release memory message, a lock request message, a read header message, a write page message, a sense request message, an allocate read message, an allocate write message, and/or a release pointer message. Paging synchronization facilitates recovery operations without the cost and overhead of prior art fault tolerant systems.

Abstract: An apparatus, system, and process are disclosed for maintaining data in an electronic storage array during multiple, concurrent drive failures. A first drive failure is recognized and the storage system controller subsequently enters a first operating mode. The storage system controller then recognizes a second drive failure and enters a second operating mode, which is different from the first operating mode, in response to the second drive failure. The second operating mode allows the storage system controller and a recovery module to access the data of the second failed drive in a controlled manner in order to attempt to recover the data on the first failed drive. Also, a pinned data module may allow write data to be written to a pinned data drive, instead of a failed drive, while the storage system controller is operating in the second operating mode.

Abstract: An apparatus for managing incremental storage includes a storage pool management module that allocates storage volumes to a virtual volume. Also included is an incremental log corresponding to the virtual volume, which maps virtual addresses to storage addresses. The apparatus may also include a replication module that sends replicated data to the virtual volume and a policy management module that determines allocation criteria for the storage pool management module. In one embodiment, the incremental log includes a lookup table that translates read and write requests to physical addresses on storage volumes within the virtual volume. The replicated data may include incremental snapshot data corresponding to one or more primary volumes. The various embodiments of the virtual incremental storage apparatus, method, and system facilitate dynamic adjustment of the storage capacity of the virtual volume to accommodate changing amounts of storage utilization.

Abstract: An apparatus, method, and system for speculative data mirroring include a rollback log that receives write data corresponding to a write operation that is directed to a storage region within a source volume. Also included is a storage control module that initiates a lock operation on a corresponding storage region within a target volume and a mirror control module configured to send the data corresponding to the write operation to the target volume without waiting for feedback regarding the lock operation. In one embodiment, initiating a lock operation may include sending a lock command to the target volume. Alternatively, the data corresponding to the write operation may initiate the lock operation. In addition, the mirror control module may initiate retransmission of the data in response to subsequent execution of the lock operation. Due to the unique configuration of the present invention, the present invention reduces latencies arising from synchronous mirroring operations, such as lock operations.

Abstract: The present invention relates to system and method of asynchronous data replication. In an embodiment, the system includes a primary host that asynchronously transmits write and sync commands where each write and sync command includes a data set ID and a sequence number. A secondary host coupled to the primary host receives the write and sync commands out of order, tracks receipt of write and sync commands, and after receipt of the write and sync commands of the data set writes blocks associated with the write commands to data storage coupled to the secondary host.

Abstract: Snapshot sets comprising snapshot criteria are created, maintained, and executed via a command set designed to facilitate managing and conducting snapshots on data distributed across multiple volumes. Snapshot criteria such as source volume, target volume, redundancy level, copy mode, and the like are added as desired to a snapshot set. Upon invocation of an execute command, the fast replication operations defined by the snapshot set are executed, providing a logically atomic data replication utility potentially involving multiple sources and targets. In one embodiment auto selection of a target may be specified, thus facilitating over-subscription of target resources. The present invention reduces the complexity of archiving data—particularly data distributed across multiple volumes such as data associated with database applications and the like.