Abstract: A system, method, and machine-readable storage medium for recovering data in a distributed storage system are provided. In some embodiments, the method includes identifying a failing storage device of a first storage node having an inaccessible data segment. When it is determined that the inaccessible data segment cannot be recovered using a first data protection scheme, a first chunk of data associated with the inaccessible data segment is identified and a group associated with the first chunk of data is identified. A second chunk of data associated with the group is selectively retrieved from a second storage node such that data associated with an accessible data segment of the first storage node is not retrieved. The inaccessible data segment is recovered by recovering the first chunk of data using a second data protection scheme and the second chunk of data.

Abstract: Systems and methods which implement a buffer for storing data to be written to a storage device when a data write operation of the storage device is determined to be outside of an acceptable parameter are disclosed. An elasticity buffer of embodiments may provide buffering on an as needed basis with respect to storage device cache flushing operations to thereby persistently store dirty write data from a storage device cache when a storage device data write is experiencing aberrant operation, such as when the data write is taking too long. The resources of the storage device cache may thus be cleaned and made available for subsequent data caching. The data may subsequently be written from the elasticity buffer to the storage device, such as after recovery action is taken with respect to the storage device, when the storage device starts completing data write operations in a timely fashion, etc.

Abstract: A system, method, and machine-readable storage medium for recovering data in a distributed storage system are provided. In some embodiments, the method includes identifying a failing storage device of a first storage node having an inaccessible data segment. When it is determined that the inaccessible data segment cannot be recovered using a first data protection scheme, a first chunk of data associated with the inaccessible data segment is identified and a group associated with the first chunk of data is identified. A second chunk of data associated with the group is selectively retrieved from a second storage node such that data associated with an accessible data segment of the first storage node is not retrieved. The inaccessible data segment is recovered by recovering the first chunk of data using a second data protection scheme and the second chunk of data.

Abstract: Systems, devices, and methods are provided for sharing host resources in a multiprocessor storage array, the multiprocessor storage array running controller firmware designed for a uniprocessor environment. In some aspects, one or more virtual machines can be initialized by a virtual machine manager or a hypervisor in the storage array system. Each of the one or more virtual machines implement an instance of the controller firmware designed for a uniprocessor environment. The virtual machine manager or hypervisor can assign processing devices within the storage array system to each of the one or more virtual machines. The virtual machine manager or hypervisor can also assign virtual functions to each of the virtual machines. The virtual machines can concurrently access one or more I/O devices, such as physical storage devices, by writing to and reading from the respective virtual functions.

Abstract: System and method for dynamic storage tiering are disclosed. A storage hot-spot in a first storage pool is detected. A first point-in-time copy of a virtual volume including the storage hot-spot is created in a second storage pool according to the detecting. Write requests directed to the virtual volume are redirected to the second storage pool. When decreased I/O activity directed to the storage hot-spot in the second storage pool is detected, the point-in-time copy in the second storage pool is reintegrated into at least one of a second point-in-time copy or the virtual volume.

Abstract: A system and method for connectivity-aware assignment of volumes among the storage controllers of a storage system is provided. In some embodiments, during a discovery phase, a connectivity metric is determined from a device discovery command. The connectivity metric is recorded into a data structure that identifies a plurality of hosts and a plurality of storage controllers of a storage system. In response to the determining of the connectivity metric, a storage controller ownership of a first volume is changed to improve connectivity between a host of the plurality of hosts and the first volume. In some such embodiments, a storage controller ownership of a second volume is changed to balance load among the plurality of storage controllers, and the discovery phase is, in part, a response to the change in the storage controller ownership of the second volume.

Abstract: A method for merging a source electronic memory storage cluster into a destination electronic memory storage cluster may include designating a source storage cluster having a first configuration; designating a destination storage cluster having a second configuration; receiving a configuration database including mapping information associated with the first configuration of the source storage cluster; merging the configuration database for the source storage cluster into the destination storage cluster; identifying a conflict between the source storage cluster configuration and the destination storage cluster configuration by comparing mapping information for the imported configuration database for the source storage cluster to mapping information for a configuration database associated with the second configuration of the destination storage cluster; resolving the identified conflict between the source storage cluster configuration and the destination storage cluster configuration; and merging the configurat

Abstract: A method includes provisioning a virtual volume from at least one storage pool of a storage array, designating at least one virtual volume segment of the virtual volume for mapping a virtual volume range to a virtual drive range, organizing the virtual volume range into a plurality of clusters, measuring a data load on each of the plurality of clusters and comparing the data load on each of the plurality of clusters to activity of the virtual volume, and reconfiguring the at least one virtual volume segment to contain a hot-spot.

Abstract: Methods and structure for reprogramming firmware in a storage controller using a virtual machine management (VMM) environment. A storage process (current firmware) in the storage controller operates in a current virtual machine (VM) under control of a hypervisor. Reprogrammed (new) firmware is loaded into a new virtual machine under control of the hypervisor. The new firmware initializes and directs the current firmware to quiesce its processing. The new firmware also requests the hypervisor to map data in the memory space of the current virtual machine into the memory space of the new virtual machine and to transfer ownership/control of devices and network addresses from the current virtual machine to the new virtual machine. The new firmware operating on the new virtual machine then takes control of the storage controller and resumes processing of requests.

Abstract: The present invention is directed to a method for completing a stripe write operation in a timely fashion to a RAID drive pool which includes an abnormally slow drive. For example, the stripe write operation either completes within a required time interval, or an error is provided to the host/initiator which provides an indication to an application that the stripe write operation did not complete.

Abstract: Systems and methods for dynamic storage tiering using snapshot functionality are disclosed. A point-in-time copy of a virtual volume including a storage hot-spot is created; write operations directed to the virtual volume may be redirected to a point-in-time temporary virtual volume. The virtual volume segment, including the hot-spot, is copied from a first storage pool to a second storage pool. Finally, a logical block address mapping of the virtual volume is reconfigured to reference the virtual volume segment copy in the second storage pool. Upon deletion of the point-in-time copy of the virtual volume, the virtual volume segment copy in the second storage pool may be updated with data from the point-in-time temporary virtual volume.

Abstract: A method for Dynamic Storage Tiering (DST) may include identifying a first storage tier with a performance characteristic. The method may include monitoring the utilization of the first storage tier to detect the placement of a hot spot. The method may include logically dividing a continuous range of a plurality of logical addresses into at least a first segment and a second segment so the first segment includes a proportionally larger amount of the hot spot. The method may include moving the first segment into a second storage tier or moving the second segment into the second storage tier. The method may include determining an amount of utilization of the first storage tier by hot spots. The method may include recommending a change in an amount of storage space in the first storage tier based upon the amount of utilization of the first storage tier by the hot spots.

Abstract: A method includes applying a write Input/Output (I/O) queue interval to a Logical Unit (LU) member of a consistency group (CG). The method also includes marking each write I/O with a timestamp and suspending I/O from the participating storage array to the LU member of the CG upon the participating storage array receiving a snapshot request from a master storage array. The method further includes determining whether the snapshot request timestamp is within the write I/O queue interval of the participating storage array.

Abstract: A method for pre-staging data includes obtaining a DST configuration of a virtual volume at a first point in time. The method also includes creating a Point-in-Time copy (PiT) in a destination storage pool when the virtual volume includes at least one PiT, or reconfiguring at least one virtual volume segment to contain a hot-spot. The virtual volume may or may not have PiTs. The method further includes recording the DST configuration, specifying the DST configuration be applied to the storage array at a second point in time, and applying the DST configuration to the storage array at the second point in time.

Abstract: The present invention is directed to a method for completing a stripe write operation in a timely fashion to a RAID drive pool which includes an abnormally slow drive. For example, the stripe write operation either completes within a required time interval, or an error is provided to the host/initiator which provides an indication to an application that the stripe write operation did not complete.

Abstract: The present invention is directed to a method for pre-emptive read reconstruction. In the method(s) disclosed herein, when a pre-emptive read reconstruction timer times out, if one or more drive read operations for providing requested stripe read data are still pending; and if stripe read data corresponding to the pending drive read operations may be constructed (ex.—reconstructed) based on the stripe read data received before the expiration of the timer, the pending drive read operations are classified as stale, but the pending drive read operations are still allowed to complete rather than being aborted, thereby promoting efficiency of the data storage system in situations when the data storage system includes an abnormal disk drive (ex.—a disk drive which endures random cycles of low read performance).

Abstract: A method for metadata management in a storage system configured for supporting sub-LUN tiering. The method may comprise providing a metadata queue of a specific size; determining whether the metadata for a particular sub-LUN is cached in the metadata queue; updating the metadata for the particular sub-LUN when the metadata for the particular sub-LUN is cached in the metadata queue; inserting the metadata for the particular sub-LUN to the metadata queue when the metadata queue is not full and the metadata is not cached; replacing an entry in the metadata queue with the metadata for the particular sub-LUN when the metadata queue is full and the metadata is not cached; and identifying at least one frequently accessed sub-LUN for moving to a higher performing tier in the storage system, the at least one frequently accessed sub-LUN being identified based on the metadata cached in the metadata queue.

Abstract: The present disclosure describes a system and method for allocating volume pieces across a redundant array of inexpensive discs (RAID). A method for allocating volume pieces across a redundant array of inexpensive discs (RAID) may comprise: (a) associating one or more volume pieces of a first logical volume with a first set of drives in a drive group; and (b) associating one or more volume pieces of a second logical volume with a second set of drives in the drive group, wherein the first set of drives in the drive group includes at least one drive which is not a member of the second set of drives in the drive group.

Abstract: A method for metadata management in a storage system may include providing a metadata queue of a maximum size; determining whether the metadata for a particular sub-LUN is held in the metadata queue; updating the metadata for the particular sub-LUN when the metadata for the particular sub-LUN is held in the metadata queue; inserting the metadata for the particular sub-LUN at the head of the metadata queue when the metadata queue is not full and the metadata is not held in the metadata queue; replacing an entry in the metadata queue with the metadata for the particular sub-LUN and moving the metadata to the head of the metadata queue when the metadata queue is full and the metadata is not held in the metadata queue; and controlling the number of sub-LUNs in the storage system to manage data accessed with respect to an amount of available data storage.

Abstract: The present invention is directed to a method for providing data element placement in a storage system via a Dynamic Storage Tiering (DST) mechanism, such that improved system efficiency is promoted. For example, the DST mechanism may implement an algorithm for providing data element placement. The data elements (ex.—virtual volume hot-spots) may be placed into storage pools, such that usage of higher performing storage pools is maximized. Hot-spots may be detected by dynamically measuring load on LBA ranges. Performance of the storage pools may be measured on an ongoing basis. Further, the hot-spots may be ranked according to load, while storage pools may be ranked according to measured performance. If a hot-spot's load decreases, the hot-spot may be moved to a lower performing storage pool. If a hot-spot's load increases, the hot-spot may be moved to a higher performing storage pool.