Abstract: Embodiments of the present disclosure relate to a system, a computer program product and a method for synchronizing data between a source disk and a target disk in a cluster by performing synchronization between a source disk and a target disk, the synchronization being performed while a plurality of application I/Os on a plurality of nodes in a cluster are configured to access the source disk; and wherein a coordinator and a plurality of workers in the cluster are configured to manage copying data from the source disk to the target disk.

Abstract: Embodiments of the present disclosure relate to a system, a computer program product and a method for synchronizing data between a source disk and a target disk in a cluster by performing synchronization between a source disk and a target disk, the synchronization being performed while a plurality of application I/Os on a plurality of nodes in a cluster are configured to access the source disk; and wherein a coordinator and a plurality of workers in the cluster are configured to manage copying data from the source disk to the target disk.

Abstract: Embodiments of the present disclosure relate to a system, a computer program product and a method for synchronizing data between a source disk and a target disk in a cluster by performing synchronization between a source disk and a target disk, the synchronization being performed while a plurality of application I/Os on a plurality of nodes in a cluster are configured to access the source disk; and wherein a coordinator and a plurality of workers in the cluster are configured to manage copying data from the source disk to the target disk.

Abstract: A computer of a data processing system includes a software encryption engine and path circuitry that initially provides one or more paths for conveying data of storage I/O requests to and from a storage device, the paths including an encrypting path having a hardware encrypting component. According to a failover technique, in a first operating state, (a) the data of the storage I/O requests is conveyed via the encrypting path with encryption and decryption of the data being performed by the hardware encrypting component, and (b) monitoring is performed for occurrence of an event indicating that the hardware encrypting component has become unavailable for encrypting and decrypting the data of the storage I/O requests.

Abstract: Embodiments of the present disclosure relate to a system, a computer program product and a method for synchronizing data between a source disk and a target disk in a cluster by performing synchronization between a source disk and a target disk, the synchronization being performed while a plurality of application I/Os on a plurality of nodes in a cluster are configured to access the source disk; and wherein a coordinator and a plurality of workers in the cluster are configured to manage copying data from the source disk to the target disk.

Abstract: A technique electronically controls commitment of a change to stored information. The technique involves accessing a reviewer database to ascertain a set of reviewers assigned to review proposed changes to the stored information. The technique further involves electronically notifying the set of reviewers to review a particular proposed change to the stored information after the set of reviewers is ascertained. Each reviewer is able to electronically approve or reject the particular proposed change to the stored information. The technique further involves (i) electronically preventing commitment of the particular proposed change to the stored information while less than a predefined number of electronic approvals has been received from the set of reviewers and (ii) electronically enabling commitment of the particular proposed change to the stored information upon receipt of the predefined number of electronic approvals from the set of reviewers.

Abstract: An improved technique migrating data from a source LUN (logical unit) to a target LUN manages control I/O's in a manner that depends on the current state of data migration and on whether the control I/O's specify that reservation information for a LUN is to be set or queried. Control I/O's specifying reservation settings during the different states of migration are treated the same way as data WRITEs during those respective states, and control I/O's specifying reservation queries during different migration states are treated the same way as data READs during those respective states.

Abstract: An improved technique for measuring I/O latency in an I/O driver of a host computing system includes obtaining the tick size of a high resolution clock of the host and setting the boundaries of I/O latency buckets at different calculated numbers of high resolution clock ticks. The I/O latency buckets are used for binning latency measurements made by the I/O driver. The boundaries of the I/O latency buckets are expressed as numbers of high resolution clock ticks and correspond to a sequence of predetermined time values. At runtime, the I/O driver measures the latency of I/O requests using timestamps obtained from the high resolution clock. The latency measurements are expressed as numbers of elapsed ticks. The I/O driver then assigns measured latency values to data buckets by comparing ticks to ticks, without the need for unit conversion or resource-intensive arithmetic.

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 data migration operation uses an error flag to protect against data corruption. During write cloning states, the error flag is set and only allowed state transitions are performed, including a non-error transition to a committed state when no device fault is recorded for a target storage device and an error transition to a setup state when a device fault is recorded for the target storage device. In a clean system shutdown, a shutdown procedure records a detected target storage device fault and clears the error flag; the recorded device fault later forces the error transition of the migration operation. During the system startup, if the error flag is set then a target storage device fault is recorded to likewise later force the error transition of the migration operation, on the assumption that a detected fault may exist but be unrecorded because the shutdown procedure did not complete during shutdown.

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: Systems and methods are provided for selecting a path through which to send data in a host-based multi-path system. In one embodiment, a system includes a management server that determines a topology of the network and analyzes a plurality of paths for sending data through the network. The management server may also create a path quality index based on the topology and the analysis, the path quality index indicating a quality of individual paths within the plurality of paths. The system further includes a host that receives the path quality index from the management server and automatically selects, based on the path quality index, a path from the plurality of paths through which to send data.

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.

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 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 processing IO requests has been described that distinguishes bogus IOs from genuine IO request failures by accessing a hardware configuration record that associates available paths with hardware components at different hardware layers traversed by the paths. When an IO request fails down a first path, a second path is selected for retrying the IO request by accessing the hardware configuration record and identifying a path that the record indicates traverses hardware components that are different from those traversed by the first path at multiple hardware layers. The chance that an IO request will fail due to faulty hardware over both the first path and the second path is thus low, such that IO failures down both the first path and the second path provide a clear indication that the IO request is bogus.

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.