Abstract: Described are techniques for performing path selection. A data operation is received for a metadevice comprising a plurality of metadevice members. A first of the plurality of metadevice members is determined. The first member is the member to which the data operation is directed. In accordance with a load balancing technique for the first metadevice member, path selection is performed to select a first of a plurality of paths. The metadevice is accessible over each of the plurality of paths. The data operation is sent over the first path.

Abstract: A system shares encryption-related metadata between layers of a storage I/O stack. Additionally, a detection mechanism ensures that certain layers within the storage I/O stack are present and cooperate with a particular protocol. Along these lines, functional components engage in an in-band communications protocol, such as a data encryption key (DEK) management protocol. The in-band communications protocol employs protocol commands and responses carried along the data path as contents of in-band transport messages and responses, such as special SCSI read commands and their responses. The protocol commands and responses include a handshake command and a handshake response used during an initial handshake operation. Each protocol command and response has a protocol signature field carrying one of distinct first and second signature values which are used to identify the presence of the protocol command or response in the transport messages and responses at different locations along the data path.

Abstract: A non-disruptive upgrade (NDU) technique involves installing and activating a first copy of a new version of an application in a temporary directory to (i) obtain control from an original version of the application while the original version is installed in an application directory and (ii) shut down the original version. The technique further involves, after the first copy of the new version obtains control from the original version and the original version is shut down, installing and activating a second copy of the new version of the application in the application directory to (i) obtain control from the first copy of the new version while the first copy of the new version is installed in the temporary directory and (ii) shut down the first copy of the new version. Such operation maintains the continuity of work at each phase of the NDU technique.

Abstract: A host computer accesses a federated storage volume at first and second frames (physical storage assemblies). The host identifies a preferred frame by (1) obtaining representative values of a performance metric for sets of paths to the volume, each set associated with a different frame, and (2) selecting the frame associated with the path set having the best representative value. In one example a response latency is used to detect different distances to the host and identify the closer frame, which will be preferred. Operating modes of the paths for non-preferred frames are set to “standby”. During subsequent operation using path selection to send storage operations to the volume, the host selects among paths in an “active” operating mode so as to access the volume at the preferred frame under normal operating condition. Standby paths are reserved for less normal operating conditions, such as when no active path is available.

Abstract: A technique oversees a path between a multipathing driver of a host computer and a volume of a data storage array. The technique involves, while the multipathing driver of the host computer sends input/output requests (IOs) to the volume of the data storage array on the path, generating an IOs-Over-Period metric based on outcomes of the IOs, the IOs-Over-Period metric providing a measure of IOs per failure over a period of path operation. The technique further involves performing a comparison operation which compares the IOs-Over-Period metric to a predefined flaky path range having a predefined lower limit and a predefined upper limit. The technique further involves, after performing the comparison operation, outputting a detection signal indicating that the path is (i) flaky when the IOs-Over-Period metric falls within the predefined flaky path range and (ii) non-flaky when the IOs-Over-Period metric falls outside of the predefined flaky path range.

Abstract: A method of performing data migration from a source storage device to a target storage device in a failover cluster includes use of a roll-forward flag to signal successful completion of a migration operation from a migration node to failover nodes of the cluster, reliably controlling host access to the target storage device to ensure that it is used only when it has been successfully synchronized to the source storage device and a commit operation has occurred that ensures that subsequent read and write operations are directed exclusively to the target storage device.

Abstract: An improved technique for storing I/O metrics includes assigning metric values to data buckets held in kernel memory. Each data bucket covers a particular range of values of a respective metric and is configured as a counter, whose count is incremented each time the multipathing driver obtains or computes a metric value that falls within the range of the data bucket. Bucket counts can be read by an external program to obtain aggregate information about I/O metrics over time. The aggregate information can be fed back to the multipathing driver to enable improved selections of paths for conveying data to and from a storage array.

Abstract: Described are techniques for determining preferred paths. A host requests first information from each of one or more ports of a data storage system. The first information includes preferred path information for a first device visible to the host through each port. The preferred path information includes one or more parameters used by said host to perform one or more mathematical calculations to determine a preferred path for transmitting to the data storage system a data operation directed to the first device. The first information is sent from each port to the host.

Abstract: A processing platform comprises at least one server, computer or other processing device having a processor coupled to a memory, and implements a plurality of modules for adaptive optimization across an information technology (IT) infrastructure. The modules include a collector configured to gather information from the infrastructure, an analyzer coupled to the collector and configured to analyze the information gathered by the collector, a policy module specifying a plurality of policy sets, and a controller that is coupled to the collector, the analyzer and the policy module. The controller is configured to adjust one or more parameters of the infrastructure via corresponding control points. Associated with the analyzer is a situational analysis framework configured to periodically select and deploy for use by the controller a particular one of the specified plurality of policy sets responsive to changing operating conditions of the infrastructure.

Abstract: In one aspect, a method of compressing data includes splitting an I/O into smaller I/Os based on a throughput of I/Os in a queue, a smaller I/O is equal or smaller than a block size. The method also includes storing the smaller I/Os in the queue. The method further includes asynchronously compressing the smaller I/Os.

Abstract: Described are techniques for upgrading a driver. A driver is installed which includes an upgrade facility, a base driver and a first set of one or more driver extension modules for processing input/output operations for one or more devices. Processing is performed to upgrade the driver using the upgrade facility. The processing includes loading one or more upgrade modules associated with a second version of said driver and performing cutover processing for each of the one or more devices.

Abstract: A computer implemented method for creating an encrypted logical unit is provided. A first identification number is received, the first identification number associated with a first encryption key used to encrypt a first logical unit. The first identification number and the first encryption key are stored at a first secure location, where the first secure location provides the first encryption key to a requester in response to receiving the first identification number from the requester, assuming the requester provides security credentials. A first metadata storage space is defined on the first logical unit, the first metadata storage space comprising a region on the first logical unit that remains unencrypted. The first identification number is stored in the first metadata storage space on the first logical unit.

Abstract: Described are techniques for indicating a state associated with a device. A request is received over a path for information about a device. A response to the request is sent. The response indicates a state regarding the device on the path. The response has a response status of good and a payload of a varying size. The payload is truncated at a location prior to that at which a device identifier for the device is expected. In accordance with the response, a state regarding the device on the path is determined.

Abstract: Described are techniques for performing path selection. A data operation is received for a metadevice comprising a plurality of metadevice members. A first of the plurality of metadevice members is determined. The first member is the member to which the data operation is directed. In accordance with a load balancing technique for the first metadevice member, path selection is performed to select a first of a plurality of paths. The metadevice is accessible over each of the plurality of paths. The data operation is sent over the first path.

Abstract: The invention provides a system to reclaim space identified as no longer in use and comprises a vLUN, a thinly provisioned mapped LUN, a mapping layer, and a data reduction engine. Chunks of data are stored at logical chunk addresses (LCAs) in the vLUN and are mapped to corresponding physical chunk addresses (PCAs) in the thinly provisioned mapped LUN. The data reduction engine performs a data reduction process on a first logical chunk of data stored at a first LCA in the vLUN, where the first logical chunk has a size that is a nonzero integer multiple of the size of the storage extent of the thinly provisioned mapped LUN. After the data reduction process, the PCA associated with the first logical chunk is no longer needed, and the thinly provisioned mapped LUN is instructed to deallocate the PCA associated with the first logical chunk that is no longer needed.

Abstract: Technology for minimizing disruptions when host data on a physical volume is encapsulated into a virtualization layer or de-encapsulated is disclosed. Evaluation of a physical volume used as data storage for a virtualization layer before committing to direct access to the physical volume is enabled by preventing direct access before presenting the physical volume directly to the host and by preventing the virtualization layer from moving data on the physical volume while redirecting to the physical volume a first plurality of I/O requests that were directed to the virtualization layer.

Abstract: Described are techniques for indicating a state associated with a device. A request is received over a path for information about a device. A response to the request is sent. The response indicates a state regarding the device on the path. The response has a response status of good and a payload of a varying size. The payload is truncated at a location prior to that at which a device identifier for the device is expected. In accordance with the response, a state regarding the device on the path is determined.

Abstract: Described are techniques for performing path selection. A data operation is received for a metadevice comprising a plurality of metadevice members. A first of the plurality of metadevice members is determined. The first member is the member to which the data operation is directed. In accordance with a load balancing technique for the first metadevice member, path selection is performed to select a first of a plurality of paths. The metadevice is accessible over each of the plurality of paths. The data operation is sent over the first path.

Abstract: Described are techniques for indicating a state associated with a device. A request is received over a path for information about a device. A response to the request is sent. The response indicates a state regarding the device on the path. The response has a response status of good and a payload of a varying size. The payload is truncated at a location prior to that at which a device identifier for the device is expected. In accordance with the response, a state regarding the device on the path is determined.

Abstract: Systems and methods are provided for selecting a path for an I/O in a storage area network. In one embodiment, a method comprises receiving path configuration information for paths associated with a host device connected to the storage area network, a listing of components within the storage area network, and a notification of a component failure within the storage area network. The method may also comprise correlating the received path configuration information, the received listing of components, and the received notification of component failure to determine one determine one or more paths associated with the host device affected by the component failure. The method may further comprise transmitting to the host device an alert for the one or more affected paths.