Abstract: One embodiment is directed to a method in a computer system including a host computer and at least one storage system including first and second storage volumes, the host computer including at least one application program executing thereon. The method comprises acts of intercepting and redirecting an access request from the at least one application program to the first storage volume to the second storage volume. Other embodiments are directed to a computer readable medium with instructions for performing the method, a host computer with at least one controller to intercept and redirect the access request. Other aspects are directed to methods in a computer system including a host computer, a first storage system including a first storage volume, and a second storage system including a second storage volume, wherein the second storage volume is a hardware mirror of the first storage volume.

Abstract: One embodiment is directed to a method in a computer system including a host computer and at least one storage system including first and second storage volumes, the host computer including at least one application program executing thereon. The method comprises acts of intercepting and redirecting an access request from the at least one application program to the first storage volume to the second storage volume. Other embodiments are directed to a computer readable medium with instructions for performing the method, a host computer with at least one controller to intercept and redirect the access request. Other aspects are directed to methods in a computer system including a host computer, a first storage system including a first storage volume, and a second storage system including a second storage volume, wherein the second storage volume is a hardware mirror of the first storage volume.

Abstract: Methods and apparatus for managing access to a plurality of storage resources in a computer system including a host computer and a storage system. The host computer comprises an application layer including at least one application program, and the computer system includes a plurality of storage resources visible to the application layer. The computer system has an access facility that grants access to the plurality of storage resources and requires a privilege level for the at least one application program to be granted access. In one aspect, requests to access one of the plurality of storage resources from the application layer are intercepted, and at least one of the intercepted requests is modified in a manner that will impact the access facility in determining whether the requestor satisfies the privilege level to be granted access to the one of the plurality of storage resources.

Abstract: Method and apparatus for managing access to one of a plurality of raw storage devices in a computer system including a host computer and a storage system. The computer system includes a plurality of logical volumes of data that are visible to the host computer and the storage system and are perceived by the host computer as comprising a plurality of raw storage devices. The host computer includes a file system/LVM mapping layer. In accordance with one aspect of the invention, a request, from a requester having less than system administrator access privileges, to perform an action directly on the one of the plurality of raw storage devices is granted, so that a logical channel is provided to directly access the one of the plurality of raw storage devices without the logical channel being mapped by the file system/LVM mapping layer. Another aspect is directed to a computer system including a host computer comprising an application layer including at least one application program.

Abstract: One aspect is directed to a method and apparatus for transferring information, through a shared storage system, between first and second processes running on first and second computers, respectively. Both computers are coupled to a data storage system, with the first computer being coupled through multiple paths. In accordance with one aspect of the invention, at least one of the multiple paths is selected through which to transfer the information between the first process and the data storage system, so that communication between the first process and the shared storage system is not constrained to any particular path. Another aspect is directed to a method and apparatus for processing an out of band control command executed by a host computer in a multi-path system and targeting a device.

Abstract: One aspect is directed to a method and apparatus for transferring information, through a shared storage system, between first and second processes running on first and second computers, respectively. Both computers are coupled to a data storage system, with the first computer being coupled through multiple paths. In accordance with one aspect of the invention, at least one of the multiple paths is selected through which to transfer the information between the first process and the data storage system, so that communication between the first process and the shared storage system is not constrained to any particular path. Another aspect is directed to a method and apparatus for processing an out of band control command executed by a host computer in a multi-path system and targeting a device.

Abstract: A method and apparatus for distributing input/output (I/O) operations among at least two paths in a multi-path computer system including a host computer, a system resource and a plurality of paths coupling the host computer to the system resource. For a next I/O operation to be assigned for transmission between the host computer and the system resource, a selection is made of one of the at least two paths for transmission of the next I/O operation based upon a state of previously assigned I/O operations queued for transmission over the at least two paths.

Abstract: Method and apparatus directed to a computer system including a host computer and an intelligent storage system that stores data accessed by the host computer, the computer system including a plurality of logical volumes of data that are visible to the host computer and the storage system and that are perceived by the host computer as comprising a plurality of raw storage devices, the storage system including a plurality of physical storage devices and at least one mapping layer that maps the plurality of logical volumes to the plurality of physical storage devices so that the data in each of the plurality of logical volumes is stored on at least one of the plurality of physical storage devices. One aspect of the invention is directed to providing the host computer with information identifying, for at least one of the plurality of logical volumes, which ones of the plurality of physical storage devices store data included in the at least one of the plurality of logical volumes.

Abstract: Method and apparatus for managing access to one of a plurality of raw storage devices in a computer system including a host computer and a storage system that is coupled to the host computer and that stores data accessed by the host computer. The computer system includes a plurality of logical volumes of data that are visible to the host computer and the storage system and are perceived by the host computer as comprising the plurality of raw storage devices. In accordance with one aspect of the invention, a request to perform an action on the one of the plurality of raw storage devices can be granted, even when the requester has less than system administrator access privileges. In accordance with another aspect of the invention, the one of the plurality of raw storage devices may have associated access privileges information.

Abstract: A method and apparatus for distributing input/output (I/O) operations among at least two paths in a multi-path computer system including a host computer, a system resource and a plurality of paths coupling the host computer to the system resource. For a next I/O operation to be assigned for transmission between the host computer and the system resource, a selection is made of one of the at least two paths for transmission of the next I/O operation based upon a state of previously assigned I/O operations queued for transmission over the at least two paths.

Abstract: A method and apparatus for managing a plurality of logical volumes in a computer system, the computer system including a processor and a storage system coupled to the processor, the storage system including at least one storage device, the storage system storing the plurality of logical volumes on the at least one storage device. At least two of the plurality of logical volumes are combined in the storage system into a virtual volume that is presented to the processor as a single logical volume. The storage system also presents the processor with information that enables the processor to deconstruct the virtual volume into the at least two of the plurality of logical volumes. Another aspect is directed to a multi-path computer system including a processor, a storage system including at least one storage device to store Y logical volumes, and X paths coupling the processor to the storage system.

Abstract: A method and apparatus for managing a log of information in a computer system including a host computer and a storage system that stores data accessed by the host computer. The computer system includes a plurality of logical volumes of data that are visible to the host and the storage system and that are perceived by the host computer as comprising a plurality of raw storage devices. The storage system includes at least one physical storage device and at least one mapping layer that maps the logical volumes to the physical storage device. In one aspect of the invention, the log includes information concerning at least one I/O operation. The information includes a first component relating to aspects of the I/O operation controlled by the host computer and a second component relating to aspects of the I/O operation controlled by the storage system. In one aspect, the host computer stores the log which includes information relating to aspects of the I/O operation controlled by the intelligent storage system.

Abstract: A method and apparatus for managing data storage in a computer system including a host computer and a storage system that stores data accessed by the host computer. A performance condition that impacts system performance is detected, and in response thereto, the data within the storage system is reconfigured to improve system performance. In one aspect, this detection and reconfiguration is done automatically within the storage system in a manner transparent to the host computer. Examples of performance conditions that can be detected and alleviated include logical volumes including hot spots that are larger than the cache storage dedicated to the volumes, data segments that are accessed frequently by the host but not sufficiently frequently so that they remain in the cache between accesses, and large data segments that are accessed frequently and sequentially by the host and are stored on the same physical device within the storage system.

Abstract: A method and apparatus for managing a plurality of logical volumes in a computer system, the computer system including a processor and a storage system coupled to the processor, the storage system including at least one storage device, the storage system storing the plurality of logical volumes on the at least one storage device. At least two of the plurality of logical volumes are combined in the storage system into a virtual volume that is presented to the processor as a single logical volume. The storage system also presents the processor with information that enables the processor to deconstruct the virtual volume into the at least two of the plurality of logical volumes. Another aspect is directed to a multi-path computer system including a processor, a storage system including at least one storage device to store Y logical volumes, and X paths coupling the processor to the storage system.