Abstract: Communicating with a tape drive emulation unit that communicates using command mode or transport mode includes the tape drive emulation unit receiving an inquiry about whether the tape drive emulation unit communicates using transport mode, the tape drive emulation unit responding to the inquiry by indicating that the tape drive emulation unit does communicate using transport mode, and the tape drive emulation unit servicing transport mode commands until receiving a release command. The tape drive emulation unit may include a front end component, a data mover/server, and a tape emulation storage device. The data mover/server may include an NFS server. A host may communicate with the tape emulation unit. The host and the tape emulation unit may be coupled using a FICON connection. A host application may send commands to the tape emulation unit and may receive commands from the tape emulation unit using command mode.

Abstract: Techniques are provided for assigning alias devices in a parallel access volume storage environment. An exemplary method for assigning alias devices by a host in a parallel access volume storage environment comprises: obtaining a next I/O (input/output) operation from a queue; obtaining a utilization factor for a plurality of available I/O processing thread in the storage controller; and assigning the next I/O operation to an alias device associated with a given one of the plurality of available I/O processing threads based on the utilization factors.

Abstract: Accessing data using a first storage device and a second storage device that is a synchronous mirror of the first storage device includes determining if the first and second storage devices support alternative mirroring that bypasses having the first storage device write data to the second storage device and choosing to write data to the first storage device only or both the first and second storage device based on criteria that includes metrics relating to timing, an identity of a calling process or application, a size of an I/O operation, an identity of a destination volume, a time of day, a particular host id, a particular application or set of applications, and/or particular datasets, extents, tracks, records/blocks. A single I/O operation may be bifurcated to provide a portion of the I/O operation to only the first storage device or to both the first storage device and the second storage device.

Abstract: Changing operational backup parameters on a storage system includes a first actor generating a request to change operational backup parameters, providing the request from the first actor to a second actor, the second actor authorizing the request, and modifying the operational backup parameters in response to the second actor authorizing the request. The first actor may be assigned a role that allows the first actor to generate the request to change operational backup parameters of the storage system and the second actor may be assigned a role that allows the second actor to authorize the request to change operational backup parameters of the storage system. The request may include a time window provided by the first actor. Authorizing a request to change operational backup parameters of the storage system may create a token and an authorization key. The token may be indicative of the request provided by the first actor.

Abstract: Using high speed data transfer protocol to transfer data between a host and a storage system includes determining if a portion of data is a candidate for being transferred using the high speed data transfer protocol if the portion is not a candidate for high speed data transfer, transferring the data using a relatively low speed data transfer protocol if the portion is a candidate for high speed data transfer, attempting to transfer the data using the high speed data transfer protocol, and if transferring the data using the high speed data transfer protocol is unsuccessful, transferring the data using the relatively low speed data transfer protocol. The high speed data transfer protocol may use a first connection and the relatively low speed data transfer protocol may use a second connection. The first connection may be a PCIe or InfiniBand connection. The second connection may be a FICON connection.

Abstract: Adapting a storage system in response to operation of a corresponding host includes determining whether the host is performing a boot up operation, determining whether the host is performing a shutdown operation, and adapting operation of the storage system in response to the host performing one of: a boot up operation or a shutdown operation. Adapting operation of the storage system may include suspending low-priority housekeeping tasks, decreasing work queue scan times to be more responsive to incoming work, moving cores from other emulations, increasing thread counts, and/or preloading specified files into cache memory of the storage system. Determining whether the host is performing a boot up operation may include making a call from the storage system to the host that causes the host to return an indication thereof. Operations that are characteristic of booting up may be determined by machine learning.

Abstract: Migrating data from a first storage device to a second storage device includes causing all data of the first storage device to be copied from the first storage device to the second storage device and causing the host computer to transition from performing I/O operations with the first storage device to performing I/O operations with the second storage device by modifying metadata used for I/O operations to change a mapping of logical devices to physical devices only after causing all data of the first storage device to be copied from the first storage device to the second storage device. Migrating data from the first storage device to the second storage device is independent of any I/O operations by the host. A data write operation from the host is acknowledged only after the data has been successfully written to both the first storage device and the second storage device.

Abstract: Providing concurrent access to a tape volume of a tape emulation unit includes a first process generating a first attachment request to attach to the tape emulation unit, generating a first unique id corresponding to the first attachment request, a second process generating a second attachment request, different from the first attachment request, to attach to the tape emulation unit, generating a second unique id corresponding to the second attachment request, and allowing the first process to access a tape volume on the tape emulation unit using the first unique id while the second process concurrently accesses the tape volume on the tape emulation unit using the second unique id. The first process may access the tape volume for writing data to the tape volume. Only one of the processes may access the tape volume for writing data to the tape volume.

Abstract: Communicating with a tape drive emulation unit that communicates using command mode or transport mode includes the tape drive emulation unit receiving an inquiry about whether the tape drive emulation unit communicates using transport mode, the tape drive emulation unit responding to the inquiry by indicating that the tape drive emulation unit does communicate using transport mode, and the tape drive emulation unit servicing transport mode commands until receiving a release command. The tape drive emulation unit may include a front end component, a data mover/server, and a tape emulation storage device. The data mover/server may include an NFS server. A host may communicate with the tape emulation unit. The host and the tape emulation unit may be coupled using a FICON connection. A host application may send commands to the tape emulation unit and may receive commands from the tape emulation unit using command mode.

Abstract: Communicating between a first device and a second device includes the first device generating command mode control words for communication with the second device, the first device converting the command mode control words into transport mode control words prior to transmitting the control words to the second device, the first device receiving transport mode control words from the second device, and the first device converting the transport mode control words received from the second device into received command mode control words. An application running on the first device may generate command mode control words for communication with the second device. The application may directly provide command mode control words to an ssch or channel subsystem layer. The first device may convert the command mode control words into transport mode control words using an ssch or channel subsystem layer. The first device may be a host computing system.

Abstract: Cloning a running computing system includes quiescing processes running on a source computing system, saving state data of the source computing system, configuring a target computing system using the state data from the source computing system, and resuming program execution at the source computing system and the target computing system. Quiescing processes running on the source computing system may include marking all of the processes on the source computing system as non-dispatchable. All external resources may be identified for the source computing system prior to quiescing processes running on a source computing system. The external resources may include devices and files. The target computing system may access data that is also accessed by the source computing system. Data accessed by the source computing system may be cloned for access by the target computing system prior to resuming program execution. The data may be cloned using snapshot copies.

Abstract: Communicating between a first device and a second device includes a first portion of the first device generating command mode control words for communication with the second device, a second portion different from the first portion converting the command mode control words into transport mode control words prior to transmitting the control words to the second device, the second portion of the first device receiving transport mode control words from the second device, the second portion of the first device converting the transport mode control words received from the second device into received command mode control words, and the second portion of the first device providing the received command mode control words to the first portion of the first device. The first portion of the first device may be an application running on the first device. The first and second devices may be coupled using a FICON connection.

Abstract: Migrating data from a first storage device to a second storage device includes causing all data of the first storage device to be copied from the first storage device to the second storage device and causing the host computer to transition from performing I/O operations with the first storage device to performing I/O operations with the second storage device by modifying metadata used for I/O operations to change a mapping of logical devices to physical devices only after causing all data of the first storage device to be copied from the first storage device to the second storage device. Migrating data from the first storage device to the second storage device is independent of any I/O operations by the host. A data write operation from the host is acknowledged only after the data has been successfully written to both the first storage device and the second storage device.

Abstract: Described are techniques for mirroring data that may include issuing, by an application on a host, a write operation that writes first data to a primary storage entity having data stored in accordance with a first format and first structure; intercepting, on the host, the write operation; and performing, on the host, first processing to process the write operation. The first processing may include: sending the write operation to a data storage system including the primary storage entity; determining whether the primary storage entity is mirrored as a second storage entity having data stored in a second format and second structure different from the first format and first structure; and responsive to determining the primary storage entity is mirrored as the second storage entity, issuing one or more second write operations to mirror the first data on the second storage entity in accordance with the second format and second structure.

Abstract: Processing an I/O operation may include the host selecting one of the available paths over which to send each I/O operation to the data storage system. The selected path may be to a particular director that has responsibility for cache slot allocation and locally accessing the cache slot predicted to include the data of the I/O operation. The host may understand the cache slot allocation algorithm used on the data storage system and how cache slots are allocated for particular logical devices and tracks or locations on the logical devices. The host may direct I/Os down a path to a particular director that has, or will allocate, the cache slot used for the I/Os. There may be multiple directors in a data storage system including a distributed global memory. Each director may locally access a group of cache slots and communicate over a fabric to access the distributed global memory.

Abstract: Accessing at least two separate physical storage devices as a single logical device includes receiving data/metadata from both of the separate physical storage devices and causing the data/metadata to appear to be coming from only one of the storage devices by spoofing data/metadata from at least one of the storage devices to appear to be coming from the other of the storage devices. Spoofing data/metadata may include revising storage device identifiers. The storage device identifiers may include serial numbers and port identifiers.

Abstract: Multiple hardware and/or software components across the host and data storage system may be capable of performing data transformation operations. In at least one embodiment, a particular one of the multiple components may be selected, per I/O operation and using information generated by a component selection tool, to perform a data transformation operation. For an I/O operation, a first component may be selected to perform a first data transformation operation and a second different component may be selected to perform a second data transformation operation. The first and second components may both be on the host, both on the data storage system, or on different ones of the host and data storage system. A host I/O driver may create a request for the I/O operation where the request includes indicators identifying the first and second components as selected for performing the data transformation operations.

Abstract: Providing I/O operations to a storage device includes selecting a portion of original I/O operations based on a first set of criteria, determining whether to subdivide each of the portion of original I/O operations that are selected according to a second set of criteria different than the first set of criteria, and converting each of the original I/O operations selected for subdivision into a plurality of subdivided I/O operations for different portions of data for a corresponding one of the original I/O operations, where at least two of the different portions are from a single track of data on the storage device. The first set of criteria may include whether the I/O operations are for multiple tracks of data and whether the storage device supports subdividing a single track. The second set of criteria may include determining a measured amount of performance improvement for previous subdivision operations.

Abstract: Providing I/O operations to a storage device includes selecting a portion of original I/O operations based on a first set of criteria, determining whether to subdivide each of the portion of original I/O operations that are selected according to a second set of criteria different than the first set of criteria, and converting each of the original I/O operations selected for subdivision into a plurality of subdivided I/O operations for different portions of data for a corresponding one of the original I/O operations. The first set of criteria may include whether the I/O operations are for multiple tracks of data. The second set of criteria may include determining a measured amount of performance improvement for previous subdivision operations. Performance of subdivided I/O operations may be monitored. A number of subdivided I/O operations may be limited by a number of available parallel I/O routes.

Abstract: Described are data replication techniques that may include receiving, on a host, a write operation that writes first data to a target location on a first logical device having storage provisioned on a first data storage system; determining, on the host and in accordance with one or more criteria, whether the first data is to be replicated on a second logical device on a second data storage system; and issuing the write operation from the host to the first data storage system, wherein the write operation denotes whether to disable replication of the first data to the second logical device on the second data storage system. Such techniques may include partitioning a single write operation into multiple write operations and setting an indicator in each of the multiple writes denoting whether remote replication of the write operation is enabled or disabled.