Abstract: Disclosed is a method for creating a virtual copy of data stored in a first memory. The virtual copy of data stored in the first memory is created in a second memory in response to a request to create a copy of all data stored in the first memory. Creating the virtual copy includes, in one embodiment, creating first and second tables in memory each one of which comprises a plurality of multibit entries. Each entry of the first table corresponds to a respective memory region of the first memory. Each entry of the second table corresponds to a respective memory region of the second memory. Each first bit of the first table indicates whether the corresponding memory region of the first memory contains valid data. Each second bit of the first table indicates whether data in the corresponding memory region of the first memory has been modified since the first table was created.

Abstract: A virtual copy of data stored in a first memory is created in a second memory. Creating the virtual copy includes, in one embodiment, creating first and second tables in memory each one of which comprises a plurality of multibit entries. Each entry of the first table corresponds to a respective memory region of the first memory. Each entry of the second table corresponds to a respective memory region of the second memory. The first bit of the first and second tables indicates whether the corresponding memory region of the first and second memories, respectively, contains valid data. The second bit of the first and second tables indicates whether data in the corresponding memory region of the first and second memories, respectively, has been modified since the creation of the first and second tables, respectively.

Abstract: Systems and methods for I/O fencing in a shared storage environment are provided. Prior to initiating an I/O request, when feasible, the current time from a local timer is compared to the current state of an interval obtained for the target device. As a result, a device reset occurring while the interval is viable does not arbitrarily end a multiphase I/O operation. However, a device reset occurring once the lease has expired results in a delay or termination of the multiphase I/O operation. As a result, multiphase I/O operations from initiating hosts that have lost contact with the shared storage environment are not allowed to corrupt the shared storage devices.

Abstract: A method, system, and computer program product for preserving the intent of a logical volume creator with the logical volume. The creator of a logical volume defines certain characteristics of that logical volume. In response to the user's requirements, the system explores the possibilities for providing the characteristics in the existing storage environment. The system then implements the logical volume and stores the intent, along with a corresponding set of rules for configuring the logical volume, with the logical volume. As a result, volume management operations like resizing the volume and evacuating data from the volume use the rules to preserve the intent of the creator. By ensuring that the logical volume consistently conforms to rules fulfilling the original intent, a consistent level of availability of the logical volume can be achieved to fulfill contractual availability requirements for storage service level agreements.

Abstract: A method, system, and computer program product for adaptively implementing capabilities of a logical volume. If a particular capability is an inherent attribute of an existing storage device, the existing storage device is chosen to implement the volume. If the particular capability is not an inherent attribute of an existing storage device, one or more storage devices are selected and configured to provide the capability. If a capacity is requested for the logical volume and a storage device provides only a portion of the capacity, multiple storage devices having the capability are combined to provide the requested capability and capacity.

Abstract: A method, system, language, and computer program product to enable a user to provide a high-level specification of storage requirements without having detailed knowledge of the underlying vendor-specific APIs and command line utilities for each possible storage device used to meet the storage requirements. The user does not specify how to implement the storage requirements. The system implements the high-level specification in hardware and/or software without further direction from the user.

Abstract: A method, system, and language to express storage requirements. The language provides keywords and rules corresponding to commands for configuring a set of storage devices to provide requested capabilities of a logical volume. The language also has keywords and constructs for defining capabilities. The language supports direct inheritance of a capability, where a template specifies another template that contains rules to be used to provide a given capability. The language also supports indirect inheritance of a capability, where a template requires a capability but does not provide an implementation of the capability. In addition, the language is processed to “merge” rules by selecting a single storage device that conforms to more than one rule when possible. Merging rules enables a minimum number of storage devices to be used to meet a given logical volume configuration and set of capabilities.

Abstract: A method, system, and computer program product to enable a user to specify an intended use for a logical volume. The logical volume is configured using an application-specific template (also referred to as a user template) for an application, where the application-specific template satisfies the intended use. Rules from the application-specific template are stored with the logical volume in addition to or as part of the intent.