Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that include a storage device configured to store a logical volume mapped between a host computer and a computer having multiple initiator ports, and a processor configured to detect a unit attention condition for the logical volume. Examples of unit attention conditions for the logical volume include management operations on the logical volume and host requests for the logical volume. Upon detecting a unit attention condition, the processor can to generate a unit attention code and a respective unique serial number in response to detecting the unit attention condition, and upon receiving an input/output (I/O) request for the logical volume from a given initiator port, the processor can convey, to the given initiator port, the unit attention code and the respective unique serial number in response to the I/O request.

Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that include configuring, by a source storage system, a logical volume to comprise source regions of the source storage system that have a mapping between a host computer and the source storage system, the source regions storing source data. The source data is copied from the source regions to target data in target regions of a target storage system, the target regions being in a one-to-one correspondence with the source regions, and the volume is reconfigured so that the target regions have the mapping between the host computer and the source storage system. In some embodiments, the mapping between the host computer and the source storage system comprises a first mapping, and upon reconfiguring the volume, a second mapping can be added between the host computer and the target storage system, and the first mapping can be deleted.

Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that include identifying, by a first computer, multiple network paths to a second computer, and splitting an input/output (I/O) request for a logical volume stored on the second computer into sub-requests. A probe request defining an association between the I/O request and the sub-requests is conveyed to the second computer, and each of the sub-requests is assigned to a respective one of the multiple network paths. Each of the sub-requests are conveyed to the second computer via the assigned respective one of the multiple network paths, and the sub-requests are received by the second computer via the multiple network paths. The second computer performs the sub-requests in response to the association, and a result of each of the sub-requests is conveyed to the first computer via the assigned respective one of the multiple network paths.

Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that include ascertaining, by a first storage system, a respective port identifier for each of one or more host ports defined to the first storage system for a logical volume stored on a second storage system. Examples of the port identifiers include WWPN and iSCSI iQN identifiers. A respective unique identifier is assigned to each of the ascertained one or more host ports, and for each of the one or more host ports, the respective port identifier and the assigned respective unique identifier are conveyed to the second storage system. Upon receiving, from one of the one or more host ports, an input/output (I/O) request for the logical volume, I/O request with the respective unique identifier of the one of the one or more host ports is conveyed to the second storage system.

Abstract: Methods, apparatus and computer program products implement embodiments of the present invention that include configuring a first storage system as a proxy for a logical volume stored on a second storage system. The first computer system receives an I/O request from a host computer for the logical volume, the host computer, and identifies a port on the second storage system for the I/O request. In some embodiments, the second storage system has multiple SCSI ports, and the identified port comprises a least busy SCSI port. A probe request verifying availability of the logical volume is conveyed to the identified port, and upon receiving a response from the second storage system verifying the availability of the logical volume for the I/O request, the I/O request is conveyed to the identified port, a result of the I/O request is received from the identified port, the result is conveyed to the host computer.