International Business Machines Corporation

Eyal Perek

Orit Nissan-Messing

Oren S Li-On

Assaf Nitzan

Rivka Mayraz Matosevich

Daniel Isaac Goodman

Eliyahu Weissbrem

Amichai Schreiber

Ayelet Shani

Oren Li-on

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.

Online migration of a logical volume between storage systems

A first storage system is configured as a proxy for a logical volume stored on a second storage system. Upon receiving a response from a second storage system verifying an availability of a logical volume for an input/output (I/O) request, the I/O request is conveyed to an identified port, a result of the I/O request is received from the identified port, the result is conveyed to a host computer.

Processing input/output requests using proxy and owner storage systems

Methods, apparatus and computer program products implement embodiments of the present invention that include detecting, by a storage system, a change in a mapping of a logical volume to one or more host ports of a host computer communicating with the storage system via a storage area network (SAN). Subsequent to detecting the change, first and second input/output (I/O) requests for the logical volume are received from a given host port, and a first unit attention message is conveyed to the given host port in response to the first I/O request. A second unit attention message is conveyed to the given host port upon determining that the storage system received the second I/O request within a specific time period commencing upon receiving the first I/O request. However, the second I/O request can be performed if the storage system received the second I/O request subsequent to the specific time period.

Safely mapping and unmapping host SCSI volumes

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.

Load balancing input/output operations between two computers

Methods, apparatus and computer program products implement embodiments of the present invention that include defining a source data volume including a first multiple of source snapshots, and storing the first multiple of the source snapshots in a first storage pool including a second multiple of storage regions having respective identifiers. Upon receiving a request to copy the source data volume to a target data volume in a second storage pool, a first given source snapshot including a first set of the storage regions is accessed, and a second given source snapshot preceding the first given source snapshot is identified, the second given source snapshot including a second set of the storage regions. A set difference of the second and the first sets of the storage regions is identified, and respective identifiers of the set difference are stored to the target volume.

Copying volumes between storage pools

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.

Impersonating SCSI ports through an intermediate proxy

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 determining, based on the unique serial number, that the processor has previously conveyed the unit attention code to any of the multiple initiator ports, to reconvey an input/output (I/O) request, receive a response for the I/O request, and convey the result to the host computer.

Unit attention processing in proxy and owner storage systems

A first storage system is configured as a proxy for a logical volume stored on a second storage system in a distributed computing environment. A probe request verifying availability of the logical volume is conveyed to an identified port, and upon receiving a response from a second storage system verifying the availability of the logical volume for an 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.

Methods, apparatus and computer program products implement embodiments of the present invention that include defining a source data volume including a first multiple of source snapshots, and storing the first multiple of the source snapshots in a first storage pool including a second multiple of storage regions having respective identifiers. Upon receiving a request to copy the source data volume to a target data volume in a second storage pool, a first given source snapshot including a first set of the storage regions is accessed, and a second given source snapshot preceding the first given source snapshot is identified, the second given source snapshot including a second set of the storage regions. A set difference of the second and the first sets of the storage regions is identified, respective identifiers of the set difference are stored to the target volume, and a target snapshot is created for the target volume.

A first storage system is configured as a proxy for a logical volume stored on a second storage system. A probe request verifying availability of the logical volume is conveyed to an identified port, and upon receiving a response from a second storage system verifying the availability of the logical volume for an 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.

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.

A first storage system is configured 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.

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.

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Petach Tikva, Israel

Eyal Perek