Abstract: A method for downgrading firmware in a controller is provided. The method includes receiving a request, by the controller, to downgrade the firmware from a current version to an older version. For a feature implemented in the current version and not implemented in the older version, the method includes determining if the feature is currently in-use by the controller. If the feature is currently in-use by the controller, the method includes warning a user and abandoning the request. If the feature is not currently in-use by the controller, the method includes checking other features implemented in the current version and not implemented in the older version, and repeating determining, providing, abandoning, and checking, and downgrading the firmware, if all of the features implemented in the current version and not implemented in the older version are not currently in-use by the controller.

Abstract: Methods and apparatuses for facilitating the management of multiple controller code versions for implementing operational aspects of storage system controllers are provided. In particular, multiple versions of storage controller code are loaded into the physical memory of a storage controller. The logical region in which a particular controller code version is loaded may be designated in metadata as a primary, secondary or other region. The controller code that is associated with a logical version designated as the primary region is selected by the storage controller for execution upon a storage controller reboot. Accordingly, time consuming copy operations are not required in order to switch between different versions of storage controller code.

Abstract: The present invention provides for the expansion of a virtual storage device. Expansion of the virtual storage device includes adding one or more additional storage device units to an existing virtual storage device. Blocks or strips included in an added storage device unit are assigned addresses, to allow the added storage capacity to be accessed immediately. In order to reestablish a pattern of data storage addresses from the original storage device units of the pre-expanded virtual storage device across all of the storage device units of the post-expanded virtual storage device, temporary storage is provided. In particular, as a strip of data is relocated to its proper post-expand location, the data occupying that location is placed in a temporary storage buffer. Data in the temporary storage buffer is then written to the proper post-expand location for that data, with displaced data being written to a second temporary storage buffer.

Abstract: A method, device, and system are provided for the efficient transfer of snapshot data during a snapshot delete action. The snapshot data to be deleted may have an older version of the same snapshot and that older snapshot may need to access the data from the newer snapshot. Instead of copying all of the snapshot data of the snapshot that is being deleted to the older snapshot, only pointers to the data are copied to the older snapshot. Additionally, snapshot data can be accessed for read functions or the like while the snapshot pointers are being copied to the older snapshot.

Abstract: A data storage system configured for efficient mirroring of data between paired redundant controllers is provided. More particularly, in response to the receipt of customer data from a host for storage, a first controller segments the received customer data into one or more frames of data. In addition, the first controller determines or associates certain metadata for each frame of customer data, and inserts that metadata in the corresponding frame. The frames, including the metadata, are provided to a secondary controller. The secondary controller stores the customer data from a received frame in memory, and stores the corresponding metadata in another location of memory that is indexed to the location where the customer data was stored. The secondary controller may also associate a count value with each frame of data in order to distinguish the most recent frame of data should frames in memory have matching metadata.

Abstract: A method, device, and system are provided for the automatically assigning identification numbers or enclosure IDs to enclosures in a data storage system. Each enclosure is assigned a unique enclosure ID that can be used to reference the enclosure in the data storage system. The enclosure IDs are generated and assigned to enclosures based on the network topology. Specifically, each enclosure is assigned an enclosure ID that not only uniquely identifies the enclosure but the enclosure ID can be used to determine the location of the enclosure in the data storage system.

Abstract: A method, device, and system for resetting snapshots are provided. The reset of a snapshot incorporates the traditional snapshot delete and snapshot create operations into a single operation. Additionally, a snapshot created under the reset operation may receive an array partition from a snapshot being deleted under the same snapshot reset operation thereby retaining its identifying characteristics.

Abstract: A method, device, and system are provided for re-initializing a backing store in a data storage system. More specifically, when all snapshots associated with a specified backing store are either being deleted or are marked for deletion the backing store is re-initialized rather than deleting each snapshot independently. The re-initialization of the backing store provides for a quicker way to delete all snapshots than could previously be achieved when each snapshot was deleted independently.

Abstract: A method, device, and system are provided for determining when to re-initialize a backing store in a data storage system. More specifically, when all snapshots associated with a specified backing store are either being deleted or are marked for deletion the backing store is re-initialized rather than deleting each snapshot independently. The re-initialization of the backing store provides for a quicker way to delete all snapshots than can be achieved by deleting each snapshot independently.

Abstract: A method and device for cloning snapshots is provided. A new snapshot can be created by cloning an existing snapshot. The clone snapshot may use the preserved data of the existing snapshot, thereby obviating the need to copy the preserved data. Additionally, the clone snapshot may be created with a data structure for storing write data. Since the clone snapshot initially has no write data to store, the creation of the entire clone snapshot can be accomplished without copying any preserved data or write data from the existing snapshot, thereby increasing the efficiency with which a clone snapshot can be created.

Abstract: A method and device for managing snapshot data is provided. Snapshots may be created having a preserved data area and a write data area. The preserved data area is used to maintain snapshot data corresponding to the point-in-time when the snapshot was created while the write data area is used to facilitate host read/write access to the snapshot. By maintaining two separate areas, the snapshot can be written to without altering the point-in-time representation of the snapshot.

Abstract: A network storage controller for transferring data between a host computer and a storage device, such as a redundant array of inexpensive disks (RAID), is disclosed. The network storage controller includes at least one channel interface module which is adapted to be connected to the host computer and storage device. The channel interface module is connected to a passive backplane, and selectively transfers data between the host computer and storage device and the passive backplane. The network storage controller also includes at least one controller memory module, attached to the passive backplane. The controller memory module communicates with the channel interface module via the passive backplane, and processes and temporarily stores data received from the host computer or storage device. In applications where redundancy is required, at least two controller memory modules and at least two channel interface modules are used.

Abstract: Methods and apparatuses for providing a data storage system having snapshot restore capabilities are provided. In particular, snapshots may be taken to represent a state of a storage volume at different times. The state of the storage volume may be returned to the state represented by any snapshot even while the storage volume continues to accept read and write operations. Furthermore, these features are provided in the context of a sparse snapshot structure, according to which multiple copies of individual data chunks are not maintained by the data storage system.

Abstract: The present invention is directed to a data storage system utilizing a number of data storage devices. Each of the data storage devices stores primary and mirrored copies of data. Furthermore, the data is arranged such that no one data storage device stores both the primary and mirrored copies of the same chunk of data. Data may be striped across the storage devices such that stripes containing primary copies of data chunks are interleaved with stripes containing mirrored copies of data chunks.

Abstract: A method, device, and system are provided for the automatically assigning identification numbers or enclosure IDs to enclosures in a data storage system. Each enclosure is assigned a unique enclosure ID that can be used to reference the enclosure in the data storage system. The enclosure IDs are generated and assigned to enclosures based on the network topology. Specifically, each enclosure is assigned an enclosure ID that not only uniquely identifies the enclosure but the enclosure ID can be used to determine the location of the enclosure in the data storage system.

Abstract: A method, device, and system are provided for rollback of a master volume in a data storage system. More specifically, when a rollback is requested, snapshots that are involved in the rollback can be deleted during the rollback. This is accomplished by deleting the snapshot partition but not the actual snapshot data. Rather, the snapshot data is retained until the rollback is complete incase some of the snapshot data needs to be written to the master volume as part of the rollback.

Abstract: A method, device, and system are provided for accessing metadata in a data storage system. More specifically, a requesting application requests a cache application to allocate a cache page to retrieve metadata from a storage device. After metadata is written to the cache page, the cache page is locked by the requesting application. The cache page is maintained in a locked state by the requesting application. This allows the data stored within the cache page to be quickly accessed and updated by the requesting application without waiting for the cache page to be written back to the storage device after every update to the cache page occurs.

Abstract: The present invention provides for a data storage system having a number of virtual storage devices. Each of the virtual storage devices may include a number of physical storage devices. The physical storage devices need not be separately addressable by a host system. Each virtual storage device unit may comprise a field replaceable unit encompassing no more than a single virtual storage device. Physical storage devices included in a virtual storage device that are not in active use may be powered down, even while one or more other physical devices included in that virtual storage device are powered up.

Abstract: A direct memory access (DMA) engine has virtually all control in connection with data transfers that can involve one or both of primary and secondary controllers. The DMA engine receives a command related to a data transfer from a processor associated with the primary controller. This command causes the DMA engine to access processor memory to obtain metadata therefrom. In performing a DMA operation, the metadata enables the DMA engine to conduct data transfers between local memory and remote memory. In performing exclusive OR operations, the DMA engine is involved with conducting data transfers using local memory.

Abstract: A method, device, and system are provided for the efficient transfer of snapshot data during a snapshot delete action. The snapshot data to be deleted may have an older version of the same snapshot and that older snapshot may need to access the data from the newer snapshot. Instead of copying all of the snapshot data of the snapshot that is being deleted to the older snapshot, only pointers to the data are copied to the older snapshot. Additionally, snapshot data can be accessed for read functions or the like while the snapshot pointers are being copied to the older snapshot.