Abstract: A data storage system comprises a controller, a first lower performance storage medium and a second higher performance storage medium. The controller is connected to the storage mediums and is arranged to control I/O access to the storage mediums. The controller is further arranged to store an image on the first storage medium, initiate a copy function from the first storage medium to the second storage medium, direct all I/O access for the image to the second storage medium, periodically age data from the second storage medium to the first storage medium, create a new empty bitmap for each period, and in response to an I/O access for data in the image, update the latest bitmap to indicate that the data has been accessed and update the previous bitmaps to indicate that the data has not been accessed.

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: An apparatus, method and computer program in a distributed cluster storage network comprises storage control nodes to write data to storage on request from a host; a forwarding layer at a first node to forward data to a second node; a buffer controller at each node to allocate buffers for data to be written; and a communication link between the buffer controller and the forwarding layer at each node to communicate a constrained or unconstrained status indicator of the buffer resource to the forwarding layer. A mode selector selects a constrained mode of operation requiring allocation of buffer resource at the second node and communication of the allocation before the first node can allocate buffers and forward data, or an unconstrained mode of operation granting use of a predetermined resource credit provided by the second to the first node and permitting forwarding of a write request with data.

Abstract: A data storage system comprises a controller, a first lower performance storage medium and a second higher performance storage medium. The controller is connected to the storage mediums and is arranged to control I/O access to the storage mediums. The controller is further arranged to store an image on the first storage medium, initiate a copy function from the first storage medium to the second storage medium, direct all I/O access for the image to the second storage medium, periodically age data from the second storage medium to the first storage medium, create a new empty bitmap for each period, and in response to an I/O access for data in the image, update the latest bitmap to indicate that the data has been accessed and update the previous bitmaps to indicate that the data has not been accessed.

Abstract: Write requests from host computers are processed in relation to a thin provisioning storage subsystem. A write request is received from a host computer. The write request identifies a first virtual disk that has been previously assigned to the host computer. It is determined whether the first virtual disk has to be allocated additional physical storage locations of the thin provisioning storage subsystem for storing data associated with the write request. In response to determining that the virtual disk has to be allocated additional physical storage locations, the following is performed. First, a quantity of free space remaining unallocated within physical storage locations of the thin provisioning storage subsystem is determined. Second, where the quantity of free space remaining unallocated within the physical storage locations satisfies a policy threshold associated with a second virtual disk, the second virtual disk is write-inhibited. The first and second virtual disks can be different.

Abstract: A data storage system comprises a controller, a first lower performance storage medium and a second higher performance storage medium. The controller is connected to the storage mediums and is arranged to control Input/Output (IO) access to the storage mediums. In operation, the controller is arranged to store an image on the first storage medium, initiate a copy function from the first storage medium to the second storage medium, direct all IO access for the image to the second storage medium, and periodically age data from the second storage medium to the first storage medium.

Abstract: Various embodiments for operating a distributed cluster storage network having a host computer system and a storage subsystem are provided. In one embodiment, by way of example only, at a first of a plurality of storage control nodes a request is received to write data to storage from the host computer system. The data is forwarded by a forwarding layer at the first of the plurality of storage control nodes to a second of the plurality of storage control nodes. Buffer resource are allocated for the data to be written to the storage by a buffer control component at each of the plurality of storage control nodes. The constrained status indicator of the buffer resource is communicated to the forwarding layer. Additional system and computer program product embodiments are disclosed and provide related advantages.

Abstract: A storage network control apparatus is operable to present virtualized storage to a host system and includes a monitoring component, an analysis component, a detection component, and a migration component. The monitoring component is for monitoring input/output (I/O) activity for virtual storage logical units over time. The analysis component is for identifying a repeating instance of peak I/O activity for a virtual storage logical unit over time and for generating a predictive signature therefrom. The detecting component is for identifying an instance of such a predictive signature. The migration component is responsive to the detecting component, and is for migrating data mapped by the virtual storage logical unit across additional real storage units to improve the I/O performance of the virtual storage logical unit prior to a recurrence of the repeating instance of peak I/O activity. A corresponding logic arrangement may be incorporated in hardware, software or a combination thereof.

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: 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 apparatus, method, and computer program for facilitating disaster recovery of a first computer system, wherein first data residing on a first storage device associated with the first computer system is recoverable from second data residing on a second storage device associated with a second computer system and wherein the second storage device is operable to have an associated state of powered up or powered down. A receiver receives an update operation for updating the second storage device. A processor updates a non-volatile storage means with the update operation, prior to update of the second storage device, wherein the non-volatile storage means is associated with the second computer system.

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: The exemplary embodiments of this invention provide in one non-limiting aspect thereof a control device operable to execute a filter layer, and includes a first interface for coupling to a first storage device and a second interface for coupling to a second storage device. The filter layer receives communications and, in a first mode, synchronously transmits the communications to the first storage device and asynchronously transmits the communications to the second storage device, and, in a second mode, synchronously transmits the communications to the second storage device.

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: A copy engine (104) is provided as an interface between firmware (108) and memory space (106) for carrying out copy operations. The copy engine has a first register (202, 203) to point to a first address and a second register (204, 205) to point to a second address. One of the first and second addresses is a source address and one is a destination address for data to be copied. The copy engine (104) also has a control register (201). The control register (201) includes a count of the amount of memory space required by a copy operation, an indication of the direction of the copy operation from the first address to the second address or from the second address to the first address, and an indication of whether the first memory address is incremented or decremented. The copy engine (104) includes a locking mechanism for locking the copy engine (104) during a copy operation. The copy engine (104) also includes a serialization mechanism in which a write is made to control register (201) of zero count.

Abstract: A storage controller includes an interface to host computer apparatus and an interface to a plurality of controlled storage apparatus. The storage controller comprises a host write component operable to send a request to write a data object to a source data image at one of said plurality of controlled storage apparatus; a copy component operable in response to a metadata state to control copying of said data object to a target data image in a delimited sequence of data images in a cascade at said plurality of controlled storage apparatus and a fill-in component operable in response to detection of an offline condition of a disk containing said target data image to control substitution of a fill-in disk in place of said disk containing said target data image.

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 method and apparatus for managing a loop network, the loop network (200) including at least one loop (206, 208), a plurality of devices (210) connected to the at least one loop (206, 208) via ports (211, 212), wherein at least two of the devices are initiators (207, 209). The method includes each initiator (207, 209) sending a frame to all other initiators (207, 209) in the loop network (200) identifying any ports (211, 212) which should not be used. Each initiator (207, 209) merges the information from all other initiators (207, 209) with its own information identifying any ports (211, 212) which should not be used resulting in all the initiators (207, 209) generating a single list of ports (211, 212) to be used which is consistent across all the initiators (207, 209). Each initiator (207, 209) applies an algorithm (300) to determine a common set of ports (211, 212) to be used by all the initiators (207, 209) and to balance port accesses across the loop network (200).

Abstract: An apparatus for data transmission over a network includes a buffer and a timer mechanism for timing an optimum interval (less than the round-trip error response delay) for retransmission of data. A first accessor accesses data in the buffer for transmission and starts a first timeout clock. Second or further accessors of the buffer are responsive to a timeout to access the data, start a timeout clock and attempt to transmit the data on a path avoiding path elements used by prior accessors. A counter increments and decrements a count of the references to the buffer by accessors and signals when the count reaches zero. A memory manager returns the buffer to a free buffer pool responsive to the reference counter signaling that the count has reached zero. An analysis mechanism can be used to determine the optimum interval and tune the timer mechanism.

Abstract: Write requests from host computers are processed in relation to a thin provisioning storage subsystem. A write request is received from a host computer. The write request identifies a first virtual disk that has been previously assigned to the host computer. It is determined whether the first virtual disk has to be allocated additional physical storage locations of the thin provisioning storage subsystem for storing data associated with the write request. In response to determining that the virtual disk has to be allocated additional physical storage locations, the following is performed. First, a quantity of free space remaining unallocated within physical storage locations of the thin provisioning storage subsystem is determined. Second, where the quantity of free space remaining unallocated within the physical storage locations satisfies a policy threshold associated with a second virtual disk, the second virtual disk is write-inhibited. The first and second virtual disks can be different.