Abstract: A storage network includes a path processor for directing data onto one of two or more paths between an application host and two or more storage controllers in a storage subsystem. To determine a data path within the storage network, the operational status of a storage controller in the storage subsystem is monitored. It is determined whether a change in the operational status of the storage controller is a failure or a potential failure. This determination is sent to the path processor. The path processor redirects application host data from the path controller on the basis of the determination.

Abstract: A storage control system comprising: one or more I/O processors for receiving requests to write data; a batch controller for selecting one or more write requests to be placed in a first batch; a first server for transmitting the first batch to a second server in a remote copy pair system; one or more I/O handlers for writing the first batch to completion on a data storage medium, in response to receiving permission from the second server; and one or more clients for communicating with the I/O processors and the I/O handlers, wherein the permission is granted when the second server is notified by the I/O handlers that previous write requests have been completed, wherein the first server is responsive to the completion of the first batch.

Abstract: This invention relates to an asynchronous remote copying (ARC) system adapted to operate as a remote copy pair by communicating between primary storage and remote storage of a remote copy pair. The system comprises a primary controller for receiving a write command and writing data to primary storage; a remote controller for receiving a write command and writing data to remote storage; an ARC controller for suppressing the release of the write command to the remote controller if a delay between receiving the write command and the time when the remote storage may accept the data is more than a threshold delay, and the primary controller suppresses recording the data in primary storage until release of the write command to the remote storage.

Abstract: A storage controller for a storage system in which there are multiple storage devices and a method for recording diagnostic information are provided. The storage controller includes a storage device manager which has means for allocating a storage device in the storage system for storing diagnostic data. The storage controller also includes means for generating diagnostic data regarding the operation of the storage controller. Two buffers are used for alternately recording and writing batches of diagnostic data to the allocated storage device. The allocated storage device may be a storage device which is normally reserved for disaster recovery in the storage system.

Abstract: An apparatus configured to operate as a primary for a remote copy pair is provided. The apparatus comprises a journal component at said primary for generating journal entries for one or more uncompleted sequenced batches; a configurator responsive to an error indication from a secondary for enumeration of said one or more uncompleted sequenced batches; and a primary server responsive to said enumeration of said one or more uncompleted sequenced batches to reissue to said secondary one or more write requests for said one or more uncompleted sequenced batches, during recovery processing.

Abstract: An arrangement and method for update of configuration cache data in a disk storage subsystem in which a cache memory (110) is updated using two-phase (220, 250) commit technique. This provides the advantage that known changes to the subsystem do not require an invalidate/rebuild style operation on the cache. This is especially important where a change will invalidate the entire cache.

Abstract: In a stacked system, errors detected at a user application interface of one or more host systems are associated with root cause errors at a stack level below a virtualization layer by detecting an error at a user application interface; identifying an associated root cause error at a lower stack level; creating an error trace entry for the error; associating an error log identifier with the error trace entry; making the combined error log identifier and the error trace entry into an error identifier that is unique within the plurality of host systems in said stacked system; and communicating the error identifier to any requester of a service at a user application interface of one or more host systems when the service must be failed because of the root cause error.

Abstract: The present invention relates to an apparatus having a memory operable with a virtualised RAID controller to determine an optimum I/O configuration by testing performance characteristics of a plurality of I/O operations.

Abstract: A log structured array (LSA) controller apparatus controls the transfer of information between a processor and a plurality of information storage devices configured as an N+1 array in which the information is stored as stripes extending across the devices of the array, each stripe comprising N information strips and one parity strip, each information strip storing an integer number of logical tracks. The controller defines an LSA directory that specifies the location of each logical track in terms of the ID of the stripe to which the track belongs and the offset of the track within the stripe; wherein on the addition of an information storage device to the array, the additional strip provided for each stripe by the storage device is logically appended to the end of each stripe in the LSA directory.

Abstract: The present invention relates to an apparatus having a memory operable with a virtualised RAID controller to determine an optimum I/O configuration by testing performance characteristics of a plurality of I/O operations.

Abstract: A method and system for reading data from a redundant array of computer data storage media elements without having to wait for a timeout in a drive in the redundant array. If the requested data is from a drive that is temporarily in a timeout, the requested data is reconstructed using other drives in the redundant array, and the reconstructed data is sent to the requester via an array controller. When the drive holding the originally requested data comes back from the timeout and responds to the original request by transmitting the original data, the array controller ignores the original data since the request has already been fulfilled by the reconstructed data.

Abstract: In a stacked system, errors detected at a user application interface of one or more host systems are associated with root cause errors at a stack level below a virtualization layer by detecting an error at a user application interface; identifying an associated root cause error at a lower stack level; creating an error trace entry for the error; associating an error log identifier with the error trace entry; making the combined error log identifier and the error trace entry into an error identifier that is unique within the plurality of host systems in said stacked system; and communicating the error identifier to any requester of a service at a user application interface of one or more host systems when the service must be failed because of the root cause error.

Abstract: A method and apparatus for detecting and preemptively ameliorating potential logic unit thrashing in a storage system having multiple I/O requesters is disclosed. In response to detecting that each of two requesters has usable access to both of the active-passive pair of controllers, one of the active-passive pair of controllers is selected to be designated as an active resource controller. In response to detecting that one of the two requesters has usable access to only one of the active-passive pair of controllers, only one of the active-passive pair of controllers is selected to be designated as an active resource controller. In response to detecting that each of the two requesters has usable access only to different ones of the active-passive pair of controllers, one of the active-passive pair of controllers is selected to be designated as an active resource controller.

Abstract: An apparatus for providing storage control in a network of storage controllers is disclosed. The apparatus includes an owner storage controller; an I/O performing component, an ownership assignment component, a lock manager and a messaging component. The ownership assignment component assigns ownership of metadata for data to an owner storage controller. The lock manager controls the locking of metadata during I/O. The messaging component passes messages among storage controllers to request metadata state, to grant locks, to request release of locks, and to signal lock release. The I/O is performed on data whose metadata is owned by an owner storage controller, subject to compliance with metadata lock protocols controlled by the owner storage controller, and any copy of the data held from time to time is maintained in a coherency relation with the data.

Abstract: An arrangement and method for update of configuration cache data in a disk storage subsystem in which a cache memory (110) is updated using two-phase (220, 250) commit technique.

Abstract: A method and system for reading data from a redundant array of computer data storage media elements without having to wait for a timeout in a drive in the redundant array. If the requested data is from a drive that is temporarily in a timeout, the requested data is reconstructed using other drives in the redundant array, and the reconstructed data is sent to the requester via an array controller. When the drive holding the originally requested data comes back from the timeout and responds to the original request by transmitting the original data, the array controller ignores the original data since the request has already been fulfilled by the reconstructed data.

Abstract: A log structured array (LSA) controller apparatus controls the transfer of information between a processor and a plurality of information storage devices configured as an N+1 array in which the information is stored as stripes extending across the devices of the array, each stripe comprising N information strips and one parity strip, each information strip storing an integer number of logical tracks. The controller defines an LSA directory that specifies the location of each logical track in terms of the ID of the stripe to which the track belongs and the offset of the track within the stripe; wherein on the addition of an information storage device to the array, the additional strip provided for each stripe by the storage device is logically appended to the end of each stripe in the LSA directory.